Ten struggling players to watch

As we head into the September stretch run, let's examine 10 players on playoff contenders who had big first halves -- most of these guys were All-Stars -- but have struggled of late.

1. Mark Trumbo, Angels

He was a deserving All-Star after a monster first half, but he's been terrible since late July: .208/.265/.268 in his last 38 games, with just three home runs and zero (zero!) doubles. Remarkably, he's got just one double in last 68 games. His strikeout rate also spiked in August (43 K's with just seven walks), As Trumbo morphs back into Dave Kingman, dare I say the Angels would be better off with Vernon Wells in left field?

2-3. Michael Bourn and Dan Uggla, Braves

Bourn also earned an All-Star spot after a .311/.366/.451 first half, but the numbers have dipped to .236/.326/.335 in the second half. Braves fans are annoyed with Uggla's .208 average, but he does lead the National League with 80 walks, so his .340 on-base percentage is still acceptable. Still, he's hitting .182 in the second half as his batting average on balls in play has dropped from .286 to .239.

4. Carlos Pena, Rays

Joe Maddon has finally benched Pena against left-handers (with Jeff Keppinger playing first base), but if you have to wonder if he should remain in the lineup against right-handers. He's hit .171/.287/.293 since the All-Star break, and only marginally better against righties -- .188/.305/.304. Maybe it's time just to play Keppinger there every day.

5. Curtis Granderson, Yankees

His all-or-nothing approach has turned into a lot of nothing of late -- .174 since July 28. He does have six home runs and 21 RBIs in that span but he's also scored just 13 runs and the Yankees are 16-17 in the 33 games he's played. There's a reason the Orioles are stilling hanging close.

6. James McDonald, Pirates

Everything has fallen apart for McDonald in the second half. After walking just 31 hitters in 110 innings before the All-Star break, he's walked 31 in 51.2 innings since the break. On Sunday, he allowed four home runs. Opponents have pounded his fastball in the second half: .321/.422/.620 with 10 home runs in 137 at-bats.

7. C.J. Wilson, Angels

He won his last start against Boston, ending an 11-start winless streak, but even that required 108 pitches through six innings as he allowed eight hits and three runs. This could be a string of bad luck; in the first half, righties had a .246 average on balls in play but that's rocketed up to .333 in the second half. His strikeout rate and K/BB ratio have actually improved in the second half and after looking through his heat maps, I don't see an obvious issue going on here. Wilson isn't the Angels starter to watch, however: The rotation combined for a 5.37 ERA in August.

8. Ryan Vogelsong, Giants

In his first 21 starts, allowed more than three runs just twice (four runs both times). But in his last four starts he allowed eight runs, eight hits and three runs in an abbreviated three-inning sting, three runs (all home runs) and then four runs in six innings against the Astros. The Giants start Monday with a fairly comfortable 4.5-game lead over the Dodgers, but they'd feel more comfortable with Vogelsong got back on track.

9. Yu Darvish, Rangers

He's fanned 10 in back-to-back starts, so maybe he's back (the second start on Aug. 28 coming on 10 days of rest). His second half ERA remains an inflated 5.71, however. With Darvish, it's all about limiting the walks. The strikeout is phenomenal and he's allowed 13 home runs in 154.2 innings, a pretty good rate for pitching half his games in Texas. If the past two starts are an indicator of what he'll do down the stretch, he may slot in as the Rangers' No. 2 postseason starter behind Matt Harrison.

10. Lance Lynn, Cardinals

Already banished to the bullpen after five straight poor starts, Mike Matheny at least expected he'd be adding another power arm to a staff looking for relief depth in front of closer Jason Motte. But Lynn -- a first-half All-Star -- has struggled in his first three relief appearances, picking up the loss on Sunday when he allowed four hits and two runs in one innings. Remember, Lynn was a big key to the Cardinals' postseason run a year ago, especially in the NLCS when he pitched 5.1 scoreless innings against the Brewers.