Statcast Pitcher Risers/Fallers - wOBA - xwOBA (Week 5)

May 1, 2018

Statcast risers and fallers for week 5 at the SP position according to xOBA - xwOBA. Andrew Le looks at starting pitchers who could be buys or sells according to sabermetrics.

We continue our RotoBaller 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 I enlighten myself on the information and tools at my disposal.

With a month of baseball in the books, most starting pitchers have logged at least five starts and the impact of single-game results on season statlines are becoming less volatile. Sure, a disastrous outing can still wreck your ratios, but stabilization is settling in. wOBA and xwOBA are two metrics popular with the hitting vernacular. Today we'll flip the script and observe pitchers with a wide delta between their wOBA and xwOBA (wOBA-minus-xwOBA).

Since wOBA measures the actual outcome value of an at-bat and xwOBA observes expected outcomes based on Statcast information (i.e. exit velocity, launch angle), we'll draw conclusions on players with large differences between the two metrics. Our argument is simple: pitchers with a lower wOBA than their xwOBA are due for a downturn. Likewise, a wOBA in excess of xwOBA means unlucky batted-ball events, and these pitchers' fortunes may become more favorable. For reference, out of 122 pitchers that have thrown over 400 pitches this season, the median xwOBA is .339.

Due for a Turnaround

All stats as of April 30, 2018

Sean Newcomb, Atlanta Braves (1-1, 4.23 ERA, 1.48 WHIP)

Sean Newcomb has posted two quality starts in five total outings. His last start against Cincinnati was great until he unraveled in the fifth, allowing four runs and taking a no-decision. Through 27.2 innings, Newcomb is 21st-best in xwOBA at .290 but carries a .318 wOBA. His delta of .028 ranks fourth unluckiest in the majors.

Newcomb holds a solid 3.65 FIP and 11.06 K/9 in 2018. He owns a below-average Hard% of 28.8% and is 17th-best in Soft% at 24.7%. He's also limited barrels (Brls), with only 2.5% Brls per plate appearance and 4.1% Brls per batted-ball event (BBE). Newcomb's batted-ball distribution suggests he's pitched better than the headline numbers, the results just haven't caught up. A 67.9% LOB% has also not been kind.

Newcomb has battled wildness, placing some blame on his account. A poor 4.55 BB/9 dilutes the strikeout prowess and has likely restricted him from unleashing his putaway pitches at will. The pitch burden of too many BBs and Ks have also limited his ability to exceed six innings in any start, further deferring the taste of sweet victory. If Newcomb can harness the walks, his strikeout talent could lead to better results. He'll get the New York Mets in his next start.

Dallas Keuchel, Houston Astros (1-4, 4.00 ERA, 1.31 WHIP)

Dallas Keuchel also sports a respectable .293 xwOBA but a .314 wOBA has resulted in an unfavorable delta of .021. Keuchel was knocked around for six earned runs on April 27 against Oakland but aside from that, it's been a hum-ho start for the former Cy Young winner.

Keuchel is currently in the top quartile of pitchers in Brl data, allowing only 3.3% Brls/PA and 4.4% Brls/BBE. He's not giving up much hard contact (23.9% Hard%) but the outlier in 2018 has been a 27.4% FB% that's the highest since his rookie season in 2012. Throughout Keuchel's career, he's held an elevated 15.5% HR/FB but this year it's 19.4%. Combine the bloated FB% with the inflated HR/FB and the concoctions for undesirable consequences are apparent.

The case for Keuchel is his long-term resume. Unlike Newcomb, Keuchel's FIP (4.79) isn't helping him in the argument. However, the prevailing HR/FB and FB% anomalies should normalize over a full season. Keuchel's fastball velocity seems fine, and the normally-killer sliders and changeups are being punished by opposing batters. Keuchel gets a tough draw against the New York Yankees this week, but his track record and promising batted-ball quality have his arrow pointing (somewhat-convincingly) up.

Other potential underachievers: Chris Archer (TB, .025 wOBA-xwOBA), Lance McCullers Jr. (HOU, .018), Jon Gray (COL, .015)

Due for a Downturn

Jarlin Garcia, Miami Marlins (1-0, 1.00 ERA, 0.81 WHIP)

Jarlin Garcia's anonymity was outed on April 17 when he achieved a victory in the Bronx against the Yankees. In his next outing, Garcia followed-up by outdueling heralded phenom Walker Buehler in a no-decision versus the Dodgers. But under the pristine hood, Garcia's 34th-worst xwOBA (.364) pairs oddly with an extraordinary wOBA of .197. His -.167 delta is the widest in the majors by a significant margin.

Garcia's ERA is currently second best in the majors, but his FIP (4.00) is 44th. The smoke and mirrors are further embellished by a .121 BABIP and 99.0% LOB%. The batted-ball results do not mesh with the Statcast data. Garcia finds himself amongst the highest in exit velocity (89.4 MPH), Brls/BBE (11.8%) and Brls/PA (8.0%). A substandard 4.0 BB/9 affirms his WHIP has wholly been attributed to lucky BBEs.

Garcia's surprise emergence has been the result of very strong pitch values for his slider and changeup. However, he's still a contact pitcher with a mediocre 6.67 K/9. Garcia could remain serviceable intermittently this season, but the present run-rate doesn't feel sustainable. Last season in 68 relief appearances, Garcia's FIP was 4.23, in-line with 2018. That seems like a realistic target for his landing spot by season's end. His next start comes at home against the Phillies.

Jake Junis, Kansas City Royals (3-2, 3.34 ERA, 0.87 WHIP)

Jake Junis started the season with 14 innings of shutout baseball and two victories. Since then, the magic has eroded gradually, culminating in a six-run implosion against the lowly White Sox where he allowed five homeruns. In terms of wOBA (.281) and xwOBA (.371), Junis holds the eighth-largest discrepancy at -.090.

After the clunker against the Southsiders, the variance in Junis' expected and actual performance has already narrowed meaningfully. While his exit velocity is average, Junis is third-highest in Brls/BBE (14.1%) and fourth in Brls/PA (10.2%). This is partially explained by the five long balls surrendered in his last outing, but batters appear to have no trouble squaring him up (19.0% HR/FB). Junis has also been the beneficiary of a 96.0% LOB% and .155 BABIP. His existing ERA is a far cry from a 5.78 FIP that is sixth-worst in the majors.

Unlike Garcia, Junis exhibits great control (1.95 BB/9) that embodies a portion of the strong WHIP. But a low-90s fastball complemented by a modest arsenal seemingly justifies the unremarkable 6.96 K/9. Junis' HR/FB clip could shrink, but batted-balls will inevitably find grass before glove; his 14.1% LD% is too depressed to hold serve. Junis gets his next opportunity against the Red Sox in Boston.

Other potential overachievers: Sean Manaea (OAK, -.109 wOBA-xwOBA), Bartolo Colon (TEX, -.075), Trevor Williams (PIT, -.071)

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