Scott Baker turning back into Twins' ace

We've spent the last month watching Cliff Lee and Justin Verlander pitch as well as any major league pitcher can. CC Sabathia and Roy Halladay keep winning, as they always do. Even the Pirates' rotation is getting some well-deserved attention with the Bucs two games over .500 entering July. I find myself rooting for the Twins' Scott Baker. Baker doesn't have a 98-mph fastball or a saw-your-hands-off cutter he throws 25 times a game. He's merely a quiet guy on a struggling Midwestern team you won't see doing any commercials, but he just finished June with a complete game, a 10-strikeout game and a nine-strikeout game and he's become as effective on his home field as any pitcher in baseball.

Baker was Minnesota's Opening Day starter in 2010, but he stumbled through a seven-start stretch last June and July, going 2-5 with a 6.30 ERA and allowing 53 hits in 40 innings. His elbow flared up and required several cortisone shots just to finish the season. He pitched through it, going 5-0, 3.18 in his last 10 starts but was relegated to long man duty in the Twins' bullpen for the playoffs before finally having bone chips removed from the elbow in October. This spring, he worked his way back into Minnesota's rotation, but only as the fifth starter, and after opening the year just 2-4 has now gone 4-1, 1.89 in his last five starts. So, what's changed?

Baker's average fastball velocity of 91.2 miles per hour ranks him only 55th among major league starting pitchers. Yet his strikeout rate with his fastball, 22.8 percent, places Baker sixth among starters, ahead of names like Verlander, Tim Lincecum and Josh Beckett. This is where the Baker case becomes something of a riddle. He's throwing his fastball with virtually the same speed and frequency which he did last season. Yet opponents, who hit .307 against the Baker fastball in 2010, are batting only .225 against the pitch this year.

As this is happening, Baker's curveball is getting pounded and he's throwing it more often, 14.2 percent of the time this season, way up from last season's 5.8 percent rate. Opposing hitters, who batted just .140 against the Baker curveball in 2010, are suddenly belting the pitch at a .333 clip this year. Pitch frequency charts clearly show a curveball that Baker primarily threw to the lower left corner of the strike zone last season now often hangs squarely in the middle of the hitting area, where it's being put into play 45 percent of the time. However, Baker's BABIP (batting average on balls in play) at spacious Target Field is down from .314 last season to .290 this season.

It appears Baker's improved fastball command and more frequent fastball/curveball mix are keeping opposing hitters off-balance, leading to more strikeouts and fewer balls hit cleanly into play. Hitters who saw the Baker curveball only 7 percent of the time with two strikes last season are seeing the curve more than twice as often as an out pitch this season, 16 percent of the time, and while the pitch is getting hit, Baker is using his home ballpark's big dimensions in his favor. Baker's home ERA has plummeted from 3.86 last season to 2.21.

While opposing hitters chase more Baker curveballs, his fastball is leading to more strikeouts. Baker's strikeout-per-nine innings rate at Target Field has increased from 7.4 to 9.5. In his past four home starts, Baker is 3-1 with a 0.29 ERA. In Wednesday's 1-0 win over the Dodgers, Baker threw 87 of his career-high 119 pitches for strikes and following the game was sixth in the American League with 101 strikeouts.

Over his past four starts, Baker has nearly doubled his curveball usage with hitters chasing the pitch twice as frequently. This has made his two-strike fastball a vastly more effective pitch. When Baker does throw his more traditional fly ball, it's staying in his big home ballpark more often and now as we enter July, it's all combined to turn Minnesota's fifth starter back into its ace.

Follow Steve Berthiaume on Twitter @SBerthiaumeESPN.