Who are the NL's top 5 first-half surprise guys?

Giants third baseman Matt Duffy is slugging .462 with a .293 average and 41 RBIs this season. Thearon W. Henderson/Getty Images

Having covered the American League’s top five surprise guys on Sunday, let’s get into the players who have made an outsized difference relative to expectations in the National League:

1. CF A.J. Pollock, Arizona Diamondbacks, 4.0 WAR, 2.8 oWAR: Pollock's top 10 WAR rating inthe NL is as high as it is in no small part because of his contributions on defense, suggested by his NL-leading 18 defensive runs saved. But his .814 OPS is also a major step forward, not least because Pollock isn’t just some hitter whose numbers get inflated by Chase Field’s infamously hitter-friendly environment. His .788 OPS at home is actually lower than his road OPS, and he’s hitting for more power outside of Arizona. That’s a huge step forward from his injury-shortened 2014 season, when he had a 1.029 OPS at home against .644 on the road.

Pollock is in his age-27 season now, so it’s unlikely that he’s going to get better, but if he’s just one of the 10 best position players in the league, what more do you want from the guy? Settle in for a good multiyear run, because adding Pollock to Paul Goldschmidt gives the Snakes the kind of every-day talent that will keep them relevant in the NL West for several seasons to come.

2. 3B Matt Duffy, San Francisco Giants, 2.7 WAR, 2.6 oWAR: Duffy hasn’t just won the Giants’ third-base job with his performance at the plate, he’s already run off the man the Giants traded for to start there before the season. Twice. A solid shortstop in the minors, it’s no surprise Duffy has taken over the hot corner duties so effectively, and as far as his bat’s playability, he hit .304 with a .387 OBP in the minors. But his lack of power, reflected in just a .104 isolated slugging rate in the minors, was supposed to be the thing that kept him from being an every-day player at a corner in the majors.

However, Duffy hasn’t just been sucked into the Giants’ vacuum at third base, he’s slugging .462, making him one of the best hitters at a position traditionally associated with power production. In offense-only wins above replacement (oWAR), Duffy ranks 13th in the NL, between Joc Pederson and Yasmani Grandal, and better than famous people such as Justin Upton and Adrian Gonzalez. He’s one of the hardest hitters to get to pop up (hitting an infield fly just 6 percent of the time), less than half the league rate. And considering he’s just 24, there is a solid chance this growth is something you can bank on. Panda who?

3. Starting pitcher Mike Bolsinger, Los Angeles Dodgers, 1.6 WAR: Although he’s had to be managed with a bit of care, averaging just 23 batters faced per start, Bolsinger has been more than just a necessary bit of depth for the Dodgers as far as helping them survive a predictable injury to the forever fragile Brandon McCarthy. Despite very careful handling and just five quality starts in 13 spins as a result, Bolsinger has generated outsized value with a tough off-speed assortment that generates a ton of ground-ball outs.

Because of his limited track record and stuff that rarely gets past 90 mph, expectations that Bolsinger might regress seem reasonable; after all, the Dodgers simply bought the former 15th-round pick from the Diamondbacks after he was designated for assignment last winter, and he was someone who had given up 4.2 runs per nine as a starter in Double- and Triple-A. But as Ben Lindbergh suggests, between his sharp breaking stuff and getting to work with a smooth receiver like Grandal, not to mention the kind of run support the Dodgers can at times conjure up, he could continue to be a solid No. 4 or 5 behind their big guns in the rotation.

4. CF Cameron Maybin, Atlanta Braves, 0.6 WAR, 2.1 oWAR: Years after it was expected that Maybin would become a star after he was the 10th overall selection in the 2005 draft -- one pick before Andrew McCutchen went to the Pirates -- the Braves' new center fielder looks as though he has finally broken through at the plate. Not that getting out of Petco Park wouldn’t do any hitter’s bat good, but Maybin is posting career-best walk and strikeout rates, as well as his best power numbers since 2011. Maybin credits the benefit of listening to Braves hitting coach Kevin Seitzer before he was even traded to Atlanta, helping him become better at going to the opposite field. The one wrinkle to Maybin’s performance is a hugely negative defensive runs saved performance (minus-14 so far), which seems especially unusual considering his projected full-season average was better than plus-10 DRS per season from the four years in which he’s played 70 or more games. Given the huge swings we’ve seen in season-to-season DRS numbers -- Gerardo Parra, anyone? -- I’m inclined to think Maybin has been more valuable to the Braves than what WAR alone suggests.

5. Chris Heston, San Francisco Giants, 0.8 WAR: We can’t forget the organizational soldier who threw a no-hitter this season, in just his 13th big league start -- still short of the fastest to achieve that distinction, but still amazing. He’s been the second-best starter in a Giants rotation still hoping its non-MadBum veterans come around in the second half. That was just one outgrowth of his improved stamina and achieving better movement on his pitches (as Eno Sarris of ESPN Insider explored), turning someone who had been expected to be a rotation temp into the surest thing the Giants have beyond Madison Bumgarner.

Honorable mention to George Kontos, Giants, 1.0 WAR: The veteran reliever, who usually comes into games when the Giants already have fallen behind, has done a great job of stanching the bleeding, not allowing any of his 25 inherited runners to score.

Christina Kahrl writes about MLB for ESPN. You can follow her on Twitter.