Pitcher Advanced Metrics Studs and Duds - wOBA-xwOBA Difference For Week 20

August 9, 2021

Connelly Doan examines pitchers whose particular difference between their wOBA and xwOBA could make them worth adding or dropping in fantasy baseball for Week 20.

Welcome back to RotoBaller’s Statcast pitcher Studs and Duds article series! Each week I have selected an advanced stat, chosen two top performers and two under-performers, and analyzed what those stats could mean for future fantasy output. This week I will focus on the difference between pitchers' weighted on-base average (wOBA) and expected wOBA (xwOBA).

wOBA is a useful stat for gauging a pitcher's overall effectiveness in keeping hitters off the base paths. xwOBA considers batted-ball profiles to calculate what a pitcher's wOBA should be. As such, looking at the difference between the two can indicate whether a pitcher has outperformed or underperformed their expected stats.

In theory, players should perform towards their expected metrics over the course of the season, but it doesn't always line up that way. There are just under two months of the season left, so let's take a look at who has had the biggest deviations from their expected performances. As I have done throughout this series, I will not focus on obvious fantasy studs for this article.

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wOBA-xwOBA Studs

All stats current as of Sunday, August 8, 2021. The MLB average wOBA-xwOBA is -0.001 (.314 wOBA, .315 xwOBA).

David Price, Los Angeles Dodgers

(4-1, 3.53 ERA, .333 wOBA, .296 xwOBA, 0.037 Difference)

This first pitcher has been fantasy relevant for many seasons and has currently found his way into a top rotation. David Price has bounced between the Dodgers' rotation and bullpen this season, but appears to be a starter at the moment. The 35-year-old veteran has pitched well, compiling a 3.53 ERA, 1.37 WHIP, and 20.6% strikeout rate over 51 innings pitched. Even more impressive, he has pitched well despite having a wOBA that is above his xwOBA. Let's take a closer look into Price's performance.  

Price's underlying metrics align with his career marks in a number of facets. He has an above-average batted-ball profile; his 86.7-MPH exit velocity is below his career mark of 88.3 MPH and his 35.4% hard-hit rate is just below his career mark of 35.5%. He also has lowered his launch angle from a career average of 12 degrees to just 5.9 degrees this season, thanks in part to a heavy usage of sinkers and changeups. His success in these categories has given him an xwOBA in the 62nd percentile of baseball. However, things have deviated between his batted-ball profile and BABIP. Despite his solid batted-ball profile, Price has produced a .322 BABIP that is a good deal above his .291 career mark. Put all of this together and it makes sense that Price's wOBA would be a considerable amount higher than his xwOBA.

Things have worked out well for Price this season, as he has been able to grab a rotation spot for a top contender and has gotten solid results despite experiencing some bad luck. The Dodgers' pitching decisions can be frustrating for fantasy managers at times, but Price appears to be a relatively high-floor pitcher in leagues. He has produced good results and the underlying stats suggest that he could do even better if things normalize.

Kenta Maeda, Minnesota Twins

(5-4, 4.69 ERA, .334 wOBA, .300 xwOBA, 0.034 Difference)

This next pitcher was considered a higher-end option heading into this season but has been one of fantasy's bigger disappointments. Kenta Maeda has followed up his career-best season for the Twins with a career worst, compiling a subpar 4.69 ERA through 19 starts. One positive thing is that his wOBA-xwOBA difference is one of the higher ones to the positive side in baseball at 0.034. Should fantasy managers hope that Maeda can come into form just in time for the fantasy playoffs?

There are a number of good signs that suggest potential positive regression for Maeda. First, his 1.32 WHIP, while a career high, is not a terrible mark, and his 25.5% strikeout rate is fine as well. Second, his batted-ball profile has been good; both his exit velocity and hard-hit rate are in the top half of baseball, and his 3.87 SIERA supports that. Finally, his .318 BABIP this season is higher than his career mark of .279 and his subpar 1.58 HR/9 rate does not align with his batted-ball profile and respectable 17.4% HR/FB rate.

Maeda's underlying contradictions mirror Price's in several ways, but unlike Price, Maeda has not yet found success. He will need to see regression towards his underlying numbers to provide fantasy value down the stretch. This is tough for fantasy managers, as they have not given up on Maeda (he is 86% rostered), but he has failed to produce more often than not. At this point in the season, it seems to make sense to hold onto Maeda if you have him and choose your matchups wisely until he shows he can perform in tough matchups. Again, regression does not always occur for players, but there are enough indicators of it for Maeda to keep the hope alive and reasonable.

wOBA-xwOBA Duds

All stats current as of Sunday, August 8, 2021.

Brett Anderson, Milwaukee Brewers

(4-5, 3.54 ERA, .309 wOBA, .365 xwOBA, -0.056 Difference)

This pitcher is one who has typically been a useful streaming option at various points throughout his career, but has never been a fantasy lock in rotations. This season Brett Anderson has made a strong case to stick in managers' lineups, compiling a 3.54 ERA and 1.25 WHIP over 17 starts. However, he has the second-highest negative difference between his wOBA and xwOBA, with his .365 xwOBA being much higher than the league average. Could he still be considered a sneaky fantasy option for the remainder of the season?

This question is interesting given Anderson's profile. He is a pitch-to-contact, ground-ball pitcher; his 14.2% strikeout rate clearly won't help in roto leagues. Further, he has gotten hit very hard, as both his exit velocity and hard-hit rate are in the bottom-five percent of baseball. However, he has done a great job keeping the ball on the ground with a launch angle of 2.4 degrees and has produced a solid .269 BABIP to show for it. His 4.42 SIERA sides with the hard contact, but that is not unusual for ground-ball pitchers.

It seems that Anderson could be a viable fantasy option for some managers at this time, despite his wOBA-xwOBA difference. His solid overall performance and the fact that he has a strong offense behind him makes him worth a look in points leagues for teams trying to push for the playoffs. He has offered a nice floor and has a profile that can allow for success around hard contact. He is not as valuable in roto leagues due to his strikeout limitations and does not make sense as an option for teams comfortably in playoff contention, but he is also not a fantasy throwaway. Anderson did exit his start Sunday after 5 innings due to calf cramping, but it does not sound at this time that the injury is a serious one.

John Means, Baltimore Orioles

(5-3, 2.79 ERA, .268 wOBA, .305 xwOBA, -0.037 Difference)

Our final pitcher has been one of the very few bright spots for the Orioles' pitching staff this season. John Means has played the part of ace perfectly, compiling a stellar 2.79 ERA and 0.92 WHIP through 16 starts. That being said, his supporting offense has struggled mightily at times this season and his wOBA-xwOBA difference is towards the top of starters at -0.037. Should fantasy managers feel comfortable trusting Means when it matters leading up to the fantasy playoffs? 

Means does not present as clear of a case as some fantasy managers may like. He has not allowed a lot of hard contact. His exit velocity and hard-hit rate are both in the top-30 percent of baseball. However, his 21.5-degree launch angle is rather terrifying, particularly in Camden Yards. Consequently, he has still allowed a 1.63 HR/9 rate and his .426 expected slugging percentage is in the bottom-28 percent of baseball. Despite all of this, Means has pitched well enough that if he pitched to his xwOBA he would still below league average.

As I said, this one is not as rock-solid as fantasy managers may want, but Means has pitched very well this season regardless. He has shown some strong underlying metrics, and his xwOBA indicates that he could still produce strong results even if he did regress. Given how well he has pitched to this point, I feel that fantasy managers shouldn't overthink things and lean on him as they have done for most of the season.

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