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Here’s a look at the top May performances in the Red Sox minor league system, the not-so-impressive performances, and other notes from the second month of the season. (SoxProspects.com prospect ranking in parentheses).

Top offensive players in May

(12) Bryce Brentz, RF, Greenville/Salem -- .356 AVG/.404 OBP/.713 SLG with 8 home runs
(14) Ryan Lavarnway, C, Portland -- .303/.393/.556 with 8 home runs
(16) Sean Coyle, 2B, Greenville -- .286/.378/.603 with 2 home runs
(29) Miles Head, 1B, Greenville – .366/.433/.624 with 5 home runs
(NR) Chih-Hsien Chiang, OF, Portland – .310/.352/.655 with 6 home runs

Brentz earned a long-deserved promotion to Salem on May 27, homered in each of his first two games in High-A and then landed on the disabled list with a wrist injury that is likely to keep him out of action until mid-June ... Lavarnway is coming around at the plate after a sub-par April, leading the system with 8 home runs in May ... Coyle spent 10 days on the disabled list with a right shoulder strain but still managed to churn out 6 doubles, 4 triples, 2 home runs, and 7 walks for the month ... Head is the early favorite for Breakout Player of the Year, upping his season OPS to .966 with a tremendous May, topping his previous career-best .669 OPS from 2010 by a wide margin ... Chiang, once considered a prospect at second base, lost some value when he was moved to left field, but he’s still just 23 and is starting to show signs that he may be able to hit like a corner outfielder.

Top pitchers in May

(15) Kyle Weiland, SP, Pawtucket – 2-2, 3.49 ERA, 1.16 WHIP, 33/12 K/BB, 28.1 IP
(21) Brandon Workman, SP, Greenville – 1-0, 2.67 ERA, 1.15 WHIP, 27/6 K/BB, 30.1 IP
(24) Alex Wilson, SP, Portland – 1-2, 2.16 ERA, 0.99 WHIP, 30/9 K/BB, 33.1 IP
(25) Chris Balcom-Miller, SP, Salem/Portland – 2.95 ERA, 0.98 WHIP, 20/7 K/BB, 21.1 IP
(NR) Matt Fox, SP, Pawtucket – 1.53 ERA, 0.92 WHIP, 24/8 K/BB, 29.1 IP

Weiland has pitched very impressively so far in 2011 and is developing into a potential impact addition to Boston’s bullpen later this season, particularly if he can cut down on the walks a bit ... Workman looks like he’s figured out Low-A competition and should be in line for a promotion to Salem at some point before the All-Star break ... Similarly, Wilson has been pitching at the Double-A level for about a year now and may get a chance to join the PawSox after the upcoming wave of rehabbing pitchers makes its way through Pawtucket ... Balcom-Miller earned himself a promotion to Portland on the final day of the month and began his Double-A career in impressive fashion, allowing only 2 runs in a six-inning complete game ... Fox has pitched admirably in a swing-man role for Pawtucket this season, providing another potential depth option for the Boston bullpen later in the year.

May underachievers

(8) Stolmy Pimentel, SP, Portland – 0-4, 7.29 ERA, 1.81 WHIP, 16/7 K/BB, 21.0 IP
(35) Luis Exposito, C, Pawtucket -- .238/.290/.286 with 1 home run
(46) Derrik Gibson, SS, Salem -- .198/.266/.267 with 0 home runs
(NR) Michael Almanzar, 3B/1B, Salem – .198/.233/.272 with 1 home run
(NR) Brock Huntzinger, SP, Portland – 0-2, 10.34 ERA, 2.49 WHIP, 10/8 K/BB, 15.2 IP
(NR) Caleb Clay, RP, Portland – 0-1, 7.07 ERA, 1.71 WHIP, 8/7 K/BB, 14.0 IP

Pimentel seriously struggles when he’s not able to establish his fastball early, and that resulted in a slew of bad outings over the course of May ... Exposito has seemed overmatched by Triple-A pitching so far in 2011, but managed to put together a string of five good games at the plate from May 15-23, when he went 10 for 21, so he could be coming around ... Former second-round pick Gibson hasn’t hit well since his stint with short-season Lowell in 2009, and hasn’t shown much in terms of improvement at the plate ... Formerly highly-touted prospect Almanzar seems like he’s a monthly member on the underachievers list, and the fact that his lines continue to get gradually worse hasn’t helped his cause ... Former third-round pick Huntzinger has been less-than-impressive in his Double-A debut this season, throwing his fastball only in the high-80s. He landed on the disabled list with a hand injury on May 21, an injury that may have affected his velocity ... Clay, a supplemental first-round pick from the 2006 draft, has allowed opposing batters to hit .318 against him for the season.

Trends

As of June 1, the leaders in batting average are Brentz at .361, Portland OF Alex Hassan at .349, and Pawtucket IF Yamaico Navarro at .329 ... The home-run leaders are Brentz with 13, Pawtucket OF Josh Reddick with 12, Head with 11, and Lavarnway with 11 ... Stolen-base leaders are Greenville OF Felix Sanchez with 17, Portland OF Jermey Hazelbaker with 15, and Salem OF Peter Hissey with 14 ... For pitchers, Portland RHP Stephen Fife and Salem LHP Chris Hernandez lead the system in wins with 5 apiece ... ERA leaders (minimum 40 IP) are Hernandez at 2.20, Balcom-Miller at 2.45, and Pawtucket LHP Andrew Miller at 2.47 ... Strikeout leaders are Greenville LHP Manny Rivera with 61, Weiland with 57, and Greenville RHP Anthony Ranaudo with 50.

In terms of upward-trending players, look for Portland 1B Jorge Padron to come around in June after some poor luck to start the season. He’s put up a BABIP of .259, struck out only 8.3 percent of the time and popped out only 4.7 percent of the time -- all indicators that balls will start to drop in as hits for the Cuban import ... Similarly, Coyle is a player to watch, not only because of his tremendously advanced approach at the age of 19 but because his peripherals indicate that he could break out in a big way in the coming months ... Miller’s fastball-changeup-slider combination has impressed in Pawtucket, but he’ll really need to improve his control and work on maintaining a consistent release point for all of his pitches if he wants to contribute at the major-league level later this summer ... Two pitchers that may have improved their stock from non-prospects to potential major-league insurance arms are system veterans Tommy Hottovy and Blake Maxwell, both of whom have excelled in the Pawtucket bullpen after receiving promotions from Portland earlier in the month ... Top pitching prospect Drake Britton showed some improvements in May after an atrocious April, holding opposing batters to a .154 average, but he still managed to walk 19 batters in 27 innings over the course of the month.

Player movement

Seven minor-leaguers were called up to the big-league club at various points in May: LHP Rich Hill, RHP Alfredo Aceves, RHP Scott Atchison, SS Jose Iglesias, OF Josh Reddick, IF Drew Sutton and RHP Michael Bowden ... Two players, LHP Hideki Okajima and OF Daniel Nava, were outrighted to Pawtucket to clear room on the 40-man roster ... RHP Kevin Millwood was signed to a minor-league deal on May 19 and is expected to joint the Pawtucket rotation on June 1 ... A slew of players received minor-league promotions this past month, including Maxwell, Hottovy and OF Che-Hsuan Lin from Portland to Pawtucket; RHP Miguel Gonzalez, LHP Cesar Cabral, Hazelbaker and Balcom-Miller from Salem to Portland; Brentz, RHP Dennis Neuman and Ranaudo from Greenville to Salem; and OF Henry Ramos, RHP Scott Swinson and RHP Chris Martin from extended spring training to Greenville ... The organization released four minor- leaguers this month, including former first-round pick Kris Johnson, former PawSox catcher Paul Hoover, and Ryan Harvey and Curtney Doran, both outfielders who were apparently unsuccessful in attempting to convert to pitching this year.

The injury front

PawSox outfielder and top prospect Ryan Kalish has been serving as a designated hitter in extended spring training and is expected to rejoin Pawtucket soon, where he’ll continue to DH for the foreseeable future ... Kalish’s outfield teammate JC Linares tore a ligament in his ankle sliding into second base on May 2; after undergoing surgery, he is expected to miss the remainder of the season ... Navarro has been rehabbing in extended spring training since straining his oblique on May 3, and he should be ready to return to the PawSox lineup in early June ... Portland SS Ryan Dent hurt his left hamstring legging out a ground ball on April 30 and has not played since ... Huntzinger has not pitched since May 22 due to an undisclosed hand injury ... Brentz hurt his wrist on May 24 while swinging in the batting cages and is expected to miss about three weeks ... Junichi Tazawa has made two rehab appearances with the Salem Red Sox after returning from April 2010 Tommy John surgery, but his velocity has dropped a few ticks to the 87-89-mph range.

Mike Andrews is the Executive Editor of SoxProspects.com and a special contributor to ESPNBoston.com.

When are the Red Sox going to finally develop a young middle-of-the-order bat?

Hands down, that’s the most frequent question I get asked from fans who want to talk about Boston’s minor league system. Everyone wants to know who will be the next David Ortiz or Manny Ramirez in the heart of the Red Sox lineup. It’s also not an uncommon complaint that the Red Sox player development staff has failed to develop a young, cost-effective power hitter, which has some truth to it. But to those lodging that complaint, I have some news: Young, cost-effective power hitters don’t grow on trees -- and they barely even exist in 2010.

In fact, a grand total of 18 players hit 30 or more home runs this season. Of those 18, only eight will be under the age of 30 by the end of the calendar year: Miguel Cabrera, Joey Votto, Carlos Gonzalez, Prince Fielder, Mark Reynolds, Josh Hamilton, Adrian Gonzalez, and Corey Hart. Eight. Only four of those eight players are still playing for the team that originally signed and developed them: Votto, Fielder, Reynolds, and Hart.

And it’s not as if all of these eight players are still cheap. Cabrera is in the third year of an eight-year, $152 million contract that pays him $20 million in 2010. Fielder is making $10.5 million this season and is likely to get upward of $16 million via arbitration this offseason -- and that’s before he becomes eligible for free agency next winter.

That leaves Votto, Carlos Gonzalez, Reynolds, Hamilton, Adrian Gonzalez, and Corey Hart as the only young, cost-effective big-time home run hitters in the league this season. And you might as well cross Reynolds’ name off that list, as his .198 batting average and league-leading 211 strikeouts don’t make him an attractive middle-of-the-order bat. Ultimately, that means you can count the number of young, cost-effective home run hitters on one hand.

Or perhaps you can count Jose Bautista, who turns 30 on Oct. 19. An intriguing story, Bautista led the majors with 54 home runs in 2010 after hitting just 13 in 2009. Already in his seventh major league organization, Toronto acquired the outfielder from Pittsburgh for a player to be named later, Robinson Diaz, in 2008. Diaz is now a backup Triple-A catcher. Meanwhile, Bautista is making just $2.4 million this season, but is in line for a raise this offseason to somewhere in the range of $8 million in arbitration. Who knows if he’ll be able to repeat his success next year at that price tag.

Another oft-heard comment is that the Red Sox just need to add some home-run pop in the middle of the lineup to compete next year. But upon a close examination of the stats, power is the least of the team’s problems. In fact, Boston’s lineup hit 211 home runs and put up a .451 slugging percentage in 2010, second-highest in the majors in both categories. Moreover, the Sox are one of only six teams in the majors that has two players with more than 28 home runs in David Ortiz and Adrian Beltre, both of whom are also in the top eight in the American League in slugging percentage.

The bad news on the power front? Beltre, Victor Martinez, and Bill Hall are all eligible for free agency this offseason, as would be Ortiz if Boston declines his $12.5 million team option for 2011. But even if any of those four return, there’s no guarantee that they can re-create their 2010 campaigns.

The good news in the short term? The Sox put up those numbers without the full-season presence of Kevin Youkilis and Dustin Pedroia. Ortiz very well may be back, and if that’s the case, the hope will be that he doesn’t repeat his atrocious Aprils from the past two seasons. If Ortiz isn’t back, Paul Konerko and Adam Dunn (39 and 38 home runs, respectively) are possible options on the free-agent market. Fielder may be available on the trade market, but if that happens, look to regularly see the headline “Prince Fielder will cost a king's ransom” this offseason.

The good news in the long term? Boston actually has a stock of potential power hitters in its minor league system. Just don’t expect a 30-home-run hitter to pop up in the next year or two. Power prospects don’t often flash that type of home run power in the minor leagues, especially when they are playing at age-advanced levels. Even when the power does pan out, it usually doesn’t come with any consistency until the player hits his late 20s or early 30s.

In the upper levels of the Red Sox system, first baseman Anthony Rizzo is at the top of the list in terms of power potential. Rizzo, 21, led the organization with 25 home runs and 42 doubles with Double-A Portland and High-A Salem in 2010, and in the process took home the Red Sox Minor League Offensive Co-Player of the Year award. He put up a .480 slugging percentage, a 17 percent line-drive rate, and a .220 Isolated Power (a stat that measures power independent of batting average, and a number that would put Rizzo in the top 40 in the majors). Of any player in the organization, Rizzo looks to be the most likely to end up as an impact middle-of-the-order bat at the major league level. He needs to work on incorporating more lower body into his swing next season, but if he continues on his upward trends, he should get a cup of coffee with the Red Sox in the second half next year on his way to becoming an everyday major league first baseman with 30+ home run potential.

Portland catcher Ryan Lavarnway shared the Offensive Player of the Year award with Rizzo after hitting .288 with 27 doubles, 22 home runs, and a .489 slugging percentage between stints in Salem and Portland in 2010. At 23, the backstop also put up a 14.5 percent line-drive rate and a .201 ISOP. If he’s able to get regular at-bats at the major league level -- a tricky proposition given his defensive skills -- it wouldn’t be surprising to see Lavarnway have a few 25- to 30-home-run seasons in his career.

Next in line comes a group of prospects who ended the season playing with Boston -- Ryan Kalish, Josh Reddick, Lars Anderson, and Yamaico Navarro. Kalish looks like a future major league regular with 25-home-run potential, but he’ll need to work on developing a more consistent approach to major league pitching. Look for Kalish to return to the majors with greater confidence in 2011.

Reddick has greater power potential than Kalish, but his lack of plate discipline calls into question whether he can crack an everyday lineup with Boston in the near future. Anderson and Navarro both have the strength and the bat speed required of a middle-of-the-order bat, but neither has shown the ability to consistently hit major league breaking pitches. At 23, both have time to develop, but Anderson very well could be passed by Rizzo on the depth chart in the next year and Navarro is projecting more as a utility player at this point.

Another potential power hitter at the higher levels of the system is Portland catcher Luis Exposito. At 6-foot-3, 215 pounds, Exposito possesses a major league body with some of the best raw right-handed power in the system. In his second year with the Sea Dogs in 2010, the 23-year-old hit .260 with 11 home runs and a .416 slugging percentage. His tendency to chase curveballs and his lack of refinement behind the dish give him some key areas that need improvement if he hopes to become an everyday catcher at the major league level, but if he can grow in those areas, he has 20-25 home run potential.

Below Double-A, it gets a lot more difficult to project who might become a middle-of-the-order bat in the majors. While a lot of young players in the Red Sox system have shown a high power ceiling in the low minors, not many have shown the all-around skills that make it a sure bet that they will develop into everyday major leaguers.

At the A-Ball level, the four names that stand out are third baseman Will Middlebrooks (.439 slugging percentage), second baseman Oscar Tejeda (.455), outfielder Jeremy Hazelbaker (.455) and first baseman Reynaldo Rodriguez (.518). Middlebrooks and Tejeda made strides in the power department in 2010, but both have a lot of development to do, particularly with respect to maintaining a consistent, disciplined approach at the plate. Hazelbaker and Rodriguez are behind the curve in terms of age advancement, both playing for Low-A Greenville at the age of 23 in 2010. However, Rodriguez led the system with a .304 ISOP during his first year in the organization. Given his interesting career path, he’s the type of player that could surprise people down the line.

Looking down the ladder even further, the most intriguing power prospects in short-season ball are outfielders Brandon Jacobs, Bryce Brentz, Henry Ramos and Kendrick Perkins. Jacobs hit 6 home runs and put up a .411 slugging percentage with Lowell in 2010 after being selected by the Red Sox in the 10th round in 2009. He has the highest power potential in the entire system, but remains a long, long way from the majors at the age of 19. Brentz, Ramos, and Perkins, all high picks from the 2010 draft, each demonstrate similar raw power but also need a lot of refinement. In 2009, Brentz led NCAA Division I with 28 home runs and a .930 slugging percentage, but he hit just .198 with a .340 slugging percentage for Lowell in 2010.

Mike Andrews is the Executive Editor of SoxProspects.com and a special contributor to ESPNBoston.com.