Statcast Pitcher Studs and Duds - xwOBA for Week 2

April 9, 2019

Connelly Doan examines the Statcast leaderboard to identify starting pitchers whose rising and falling xwOBA could make them worth adding or dropping in fantasy baseball for Week 2.

Welcome to the first edition of Statcast pitchers analysis this season! Statcast provides a ton of interesting and insightful advanced metrics that we can use to predict future fantasy performance. Each week we will select one of these stats and choose two risers and two fallers to analyze and ultimately determine what those stats could mean for future fantasy output. Expected weighted on-base average, or xwOBA will be our first advanced stat of the 2019 season.

Before we use the stat, it is important to define it. wOBA is used to establish the value a player brings per plate appearance using unintentional walks, base hits, and hit-by-pitches; it is scaled like on-base percentage. Expected wOBA takes xOBA but applies weights to each factor to predict what the factors should have been. xwOBA provides adjusted run expectancies of a batting event in the context of the season as a whole. MLB.com and FanGraphs have great sabermetric libraries for those of you interested in reading even more about the stat.

Expected values are helpful for us, especially early on in the season because they provide predictive power for future performance. We could compare pitchers’ actual wOBA to their xwOBA to find underachievers and overachievers, but that exercise will be more useful once we have a larger set of data in 2019 (stay tuned for a later article edition!). For now, we will just compare pitchers’ 2018 xwOBA to their current xwOBA. Without further ado, let’s get going! 

xwOBA Risers

For reference, the current MLB xwOBA average against for pitchers is .321. All stats current as of Monday, April 8.

Jordan Zimmermann - Detroit Tigers

2018 xwOBA: .328; 2019 xwOBA: .181

Our first riser has a much-improved xwOBA from last season and currently has the fourth-lowest in baseball. Jordan Zimmermann used to be a household fantasy name when he was with the Nationals, but things went downhill once he joined the Tigers. However, Zimmermann currently has a 0.66 ERA and a 0.59 WHIP with 10 strikeouts and just one walk in 13 ⅔ IP. Has he found his fantasy brilliance again as his xwOBA suggests?

Let’s first try to find what is different for Zimmermann now compared to 2018. The two things that are improved are his hard-hit rate (26.3% vs 38.4% in 2018) and whiff rate (29.4% vs 20.7% in 2018). Those are about the only things that are different. His average exit velocity is about the same, his launch angle has actually increased (21 degrees vs 16.3 degrees in 2018), his pitch velocity and spin rates are about the same across the board, and his strikeout rate is about the same despite the increased whiff rate.

In sum, not much seems to have changed for Zimmermann from 2018, when he was mediocre and hardly fantasy relevant. He is now 32 years old and hasn’t made a fantasy impact since 2015, so it seems unlikely that he has suddenly tapped into some unfound talent. I am not going to buy into Zimmermann until I see a significant, longer-lasting change in his game.

Luis Castillo - Cincinnati Reds

2018 xwOBA: .320; 2019 xwOBA: .193

Our second riser showed fantasy potential in his rookie season in 2017, regressed in 2018, and hopefully is righting the ship in 2019. 26-year-old Luis Castillo currently has the sixth-lowest xwOBA in baseball along with a 1.42 ERA, a 0.79 WHIP, 17 strikeouts and seven walks in 12 ⅔ IP. Fantasy players gave up on Castillo in 2018; is now the time to buy into him before he breaks out?

Castillo has always had a strong arsenal of pitches and nothing seems to have changed; the average velocity and spin rates of his fastball, changeup, sinker, and slider are all similar to last season. Everything he has done with that arsenal so far has been positive. Castillo’s hard-hit rate is down (12.5% vs 39.5% in 2018) and his K% (34.7% vs 23.3% in 2018) and whiff% (43.8% vs 28.8% in 2018) are up significantly. Most importantly, Castillo has a career-low launch angle of three degrees and consequently has not allowed a home run this season. The long ball was Castillo’s enemy last season, as he allowed 28 (a lackluster 1.49 HR/9 rate).

The walks are a bit high, but that is really the only discouraging thing that can be said about Castillo’s performance in 2019. Despite the high walks, he still has a very low xwOBA. His current .193 xwOBA is unrealistically low, but it is not unrealistic that he has finally figured things out on the mound. If this proves to be the case, Castillo will be an extremely useful fantasy asset for this season and more to come.

xwOBA Fallers

For reference, the current MLB xwOBA average against for pitchers is .321. All stats current as of Monday, April 8.

Chris Sale - Boston Red Sox

2018 xwOBA: .237; 2019 xwOBA: .432

Our first faller has been one of baseball’s best starters of his generation and had the lowest xwOBA in all of baseball in 2018. Chris Sale has stumbled out of the gate in 2019, posting an inflated 8.00 ERA and 1.44 WHIP with just five strikeouts over nine IP spanning two starts. Accordingly, he currently is tied for the ninth-highest xwOBA in baseball. Why has his xwOBA increased so much and what does it say about what’s to come?

The root of the issue could be tied to Sale’s velocity. Sale landed on the disabled list (now injured list) twice last season for shoulder inflammation in his throwing shoulder and the effects were noticeable in his postseason performances. The biggest effect was diminished velocity in his fastball, and that looks to be carrying over into 2019. Sale’s average fastball velocity in 2018 was 95.4 MPH; his average in 2019 so far sits at 90.7 MPH, which is a significant decrease.

The decrease in velocity has affected Sale across the board in 2019. His strikeout rate (11.9% vs 38.4%) is down, while his walk rate (9.5% vs 5.5%), hard-hit rate (38.7% vs 27.1%), average exit velocity (86.2 MPH vs 84.8 MPH), and average launch angle (13.8 degrees vs 12.4 degrees), and barrel percentage (12.9% vs 7.2%) are all up compared to his 2018 stats. These changes all give hitters a better chance of either hitting the ball well or walking against Sale to get on base.

It is true that pitchers have been able to change their pitching style to remain successful after losing their velocity. However, Sale has always been a hard-throwing strikeout pitcher and the velocity decrease has been a sudden, severe shift. Given his historic caliber, we should give him an opportunity to prove himself. That being said, he could be significantly underwhelming compared to preseason expectations if his velocity does not pick up.

Kyle Hendricks - Chicago Cubs

2018 xwOBA: .297; 2019 xwOBA: .497

Our second faller has posted a pair of lackluster starts to begin the season. Kyle Hendricks has always been a useful fantasy starter, providing low ERA’s using pinpoint command, but that has not been the case in 2019. Hendricks currently has a 6.48 ERA and a massive 2.64 WHIP with eight strikeouts and four walks in 8 ⅓ innings pitched. His xwOBA is eighth-highest in baseball and fantasy owners may be concerned. Let’s look deeper to see if they should be.

Two things stand out among Hendricks’ stats. The first is his insanely high WHIP. As a control artist, Hendricks has a career WHIP of 1.13 and has never posted a season WHIP above 1.19. This suggests to me that his current 2.64 WHIP has been the result of some bad outings and a small sample size. I would expect some positive regression here, which will lower Hendricks’ xwOBA over time. The second stat of importance is Hendricks’ walk rate. The 29-year-old has a career 5.9% BB%, compared to an 8.5% BB% in 2019. WHIP and BB% are related, so I expect positive regression on Hendricks’ BB%, which in turn will help his WHIP.

Hendricks’ high xwOBA seems to boil down to an early lack of command. He has done a good job of keeping his changeup down in the zone but has missed up and in the middle of the plate with his other pitches. As such, he currently has a career-high average exit velocity, launch angle, and hard-hit rate. Again, this has come from two starts; based on his history, I expect Hendricks to find his command and pan out as expected over the course of the season. He is a buy-low candidate from early disgruntled fantasy owners.

More 2019 Fantasy Baseball Advice