August Starting Pitching NL Overachievers

There are a few pitchers that stand out as overachievers in August with numbers that are not likely to hold up down the stretch in the final month of the regular season. Here are four National League arms who look due for a correction as the calendar turns to September.

Brandon Pfaadt – Arizona Diamondbacks

Pfaadt's turnaround is one of the best stories of the second half. Since returning from a minor-league demotion on June 30, he's sitting on a 1.16 ERA and 0.89 WHIP over his last nine starts, and a 3.11 ERA for the season. The problem is what's missing: a strikeout rate that's fallen to a 5.4 K/9 since the All-Star break, an incongruent combination for anyone running ratios this shiny. Among 60 qualified pitchers since June 30, Pfaadt ranks 10th in BABIP at .237, 11th in strand rate at 86.1%, and first in HR/FB rate at a microscopic 1.6%. Despite sitting first in ERA among that group, he ranks 44th in SIERA. Arizona's defense is genuinely excellent and deserves real credit, but a starter with almost no strikeouts leaning this heavily on contact management and home-run suppression is not a stable proposition heading into the stretch run as Arizona looks to claim a wild card spot. 

Clay Holmes – Chicago Cubs

Holmes has been a quietly excellent midseason trade addition, working to a 2.49 ERA and 1.11 WHIP with 50 strikeouts against 23 walks in nearly 69 innings since being acquired from the Mets. But his expected ERA sits at 4.05, which is a run and a half higher than what he's actually allowed, and his expected wOBA against of .311 is well above his actual mark of .262, a gap of roughly 50 points. That disparity points squarely to contact-quality luck rather than a real step forward in stuff. An 6.2 K/9 for a starter this reliant on soft, well-placed contact leaves very little margin if the quality of contact normalizes, and his ground-ball-heavy approach means one string of bloopers or misplayed line drives could unravel the ratios in a hurry.

Robbie Ray – San Diego Padres

Ray has bounced between two rotations this season but has kept his ERA in a tidy 3.21, propped up by a .244 BABIP and an 80% strand rate that both sit on the fortunate side of normal. His strikeout rate is 7.7 K/9 is on pace for a career low for a pitcher who's built a career on missing bats, and a 4.4 BB/9 leaves little margin for error. His SIERA has run close to 4.95 for the season which is nearly two runs higher than his actual ERA, one of the widest gaps among qualified NL starters. Ray's stuff has proven real through his well-traveled career and he's shown he can dominate in stretches, but the profile underneath the ERA right now looks more like a mid-4.00s pitcher who's gotten a lot of help from sequencing and defense.

Michael King – San Diego Padres

King rounds out a group of pitchers sitting on sub-3.50 ERAs with strikeout-minus-walk rates no higher than 12% in at least 100 innings, which is a combination that tends not to last. He's carrying a 3.23 ERA and 1.17 WHIP with a 7.7 K/9 through 156 innings, solid volume production for a Padres staff that's needed it. But the SIERA marks for this whole tier of pitcher have run in the 4.30s to 4.90s, and King is no exception. The skill indicators simply don't support an ERA this far under 3.50. He's a legitimately useful innings-eater and his low walk rate is a real strength, but anyone pricing him as an ace-caliber arm down the stretch in big games in the NL wild card race is paying for results that look considerably better than the process behind them.