Statcast Pitcher Risers/Fallers - xwOBA Trends (Week 24)

Welcome back to Rotoballer’s series using Statcast to extrapolate, dig into, and commiserate over data to examine pitching performances. The weekly series will be dynamic as we fine-tune our findings and enlighten ourselves on the information and tools at our disposal.

Here at RotoBaller’s analytics division, we’ve experienced reasonable success discussing xwOBA and its relation to pitchers’ fortunes. Expected outcomes based on Statcast data has validated the importance of understanding advanced stats to form expectations on future results.

For week 24, we’ll ride the wave and discuss trends in xwOBA for starters since August. In our pool of 107 pitchers, the median xwOBA is .316, in-line with earlier this season. Let’s get to the findings.

Bound to Pop

All stats as of September 10 for starting pitchers with over 500 pitches since August 1.

Zack Wheeler, New York Mets (10-7, 3.39 ERA, 1.17 WHIP, 9.04 K/9)

Like many fantasy enthusiasts, I left Zack Wheeler for dead following a multi-year injury and disastrous return in 2017. Through July, Wheeler held a .312 xwOBA with expectedly pedestrian results (4.11 ERA). Since the calendar flipped to August, Wheeler’s rocked a .240 xwOBA, third-best in baseball.

Over that span, Wheeler’s registered six quality starts in seven outings with a 1.53 ERA and 0.85 WHIP. Significantly, he’s dropped his BB/9 from 3.14 to 1.91. The newfound control and uptick in velocity has led to improved pitch values across the board. Wheeler has harnessed more break in his curveball, increasing its whiff rate from around 10% to 24%. His 3.28 FIP suggests the good times are sustainable.

If everything goes as planned, Wheeler should have four more chances in 2018. While the Metropolitans have a daunting final stretch, Wheeler may draw the Marlins twice. Through his travails, it’s easy to forget Wheeler is only 28 years old. With his velocity, movement and control trending the right way, he’s approved for rest-of-season usage.

Wei-Yin Chen, Miami Marlins (6-10, 4.72 ERA, 1.32 WHIP, 7.45 K/9)

Wei-Yin Chen had a nightmare start to 2018 with a 5.86 ERA and .318 xwOBA across his first 17 starts. Since August, Chen’s rebounded with a .270 xwOBA (10th-best) and corresponding 2.04 ERA.

While Chen’s overall resume is unflattering (4.46 FIP, 3.19 BB/9), he could prove useful if he maintains the current momentum. Chen’s abandoned a mediocre four-seamer and leaned on his slider, increasing its usage to 30%. Opponents slugged a paltry .290 against the pitch in August and its success has also dampened the damage inflicted on his other pitches.

Chen’s barely rostered in most fantasy leagues so he could be a sneaky weapon in the final weeks. Streamers should certainly note his 1.77 ERA at home compared to a grotesque 9.13 away. Chen likely has three starts left, one visiting the Mets and one start apiece at home and away against the Nationals. Prior to a rude welcoming to the National League in 2016 and injuries, Chen was serviceable. Now healthy, he could return to fantasy relevance at the perfect time.

Other possible risers: Kyle Hendricks (CHC, .255 xwOBA since August), David Price (BOS, .270), Lance Lynn (NYY, .272)

Due to Drop

Jon Gray, Colorado Rockies (11-7, 4.69 ERA, 1.29 WHIP, 9.61 K/9)

Much has been made of Jon Gray’s tough luck. For a guy who flirted with a BABIP near .400, that is merited. But luck should be evaluated on both ends, and Gray’s xwOBA has deteriorated from .291 to .359 since August, 13th-highest in baseball.

The factors that hinted at inevitable mean reversion have disappeared. Gray’s BABIP (.317) and LOB% (68.3% LOB%) are ordinary. Bad luck has been replaced by a loss in fastball velocity of almost 2 MPH since Opening Day. Gray’s diminishing four-seamer has yielded to a more predictable slider, which has suffered a severe dip in whiff rate from 28% to 13%. Opponents slugged an unsettling .407 against his fastball and .434 versus the slider in August.

Despite these warnings, Gray’s escaped with “just” a 3.91 ERA across his last seven starts. His splits home and away from Coors Field are benign, but he faces a tough final schedule (ARI, at LAD, at ARI, WAS). While his 3.71 FIP indicates Gray could have a strong finish, a looming blowup outing could be detrimental for fantasy championship dreams.

Madison Bumgarner, San Francisco Giants (5-6, 3.30 ERA, 1.24 WHIP, 7.74 K/9)

Dirt biking, snot rockets and postseason heroics are just a few things that make Madison Bumgarner legendary. Unfortunately, injuries have wrecked his past two campaigns. Bumgarner only tossed 257 pitches through July, but since then he’s recorded a very unmythical .347 xwOBA, 27th-highest in the majors.

Trends are worrisome for the 29-year-old workhorse. Fastball velocity appears in structural decline since 2015 and associated pitch values have followed. His fastball is averaging just 90.8 MPH this season and a -1.73 wFB/C would rank second-worst if he qualified. Opponents squared up the heater to a slugging percentage of .700 in August. To Bumgarner’s credit, he’s heavily pivoted towards his cutter, but favorable results haven’t been tangible (36% LD%).

Whether Bumgarner is at the doorstep of father time or if his season was simply disrupted by injury is to be determined. But he should not be trusted as an ace in fantasy when reliability matters most. Bumgarner is slated for three more starts this season but it doesn’t seem farfetched the Giants shut him down early. Fantasy managers should consider the same thing.

Other possible fallers: Jon Lester (CHC, .374 xwOBA since August), J.A. Happ (NYY, .346), Zack Greinke (ARI, .339)