Pitcher Advanced Metrics Studs and Duds - xwOBA For Week 2

Welcome to the first edition of RotoBaller’s Statcast pitcher Studs and Duds article series for the 2022 season! I am happy to be back at the helm for this series once again. Statcast provides a ton of insightful advanced metrics that can be used to better understand pitchers' performance and predict future fantasy performance. Each week, I will select one of these stats and choose two pitchers with strong metrics and two with poor metrics to analyze and ultimately determine how they may perform in the future. Expected weighted on-base average, or xwOBA, will be the first advanced stat of the season.

It is important to define a metric to understand how to interpret it for fantasy purposes. 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 wOBA 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 more about the stat.

Expected values are helpful for fantasy valuations, especially early in the season because they hold predictive power for future performance. The difference between pitchers’ actual wOBA and xwOBA is a useful metric to find underachievers and overachievers, but that exercise will be more useful once there is a larger set of data in 2022 (stay tuned for a later article edition). For now, I will just compare pitchers’ 2021 xwOBA and their first couple of starts this season. Without further ado, let’s dive in!

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xwOBA Studs

All stats are current as of Sunday, April 17, 2022.

Ranger Suarez, Philadelphia Phillies

2021 xwOBA: .250

2022 Stats: (1-0, 5.87 ERA, .348 xwOBA)

This first pitcher came out of nowhere last season and likely helped fantasy managers win championships. Ranger Suarez started the season in the bullpen but ended up in the Phillies rotation, going 8-5 with a 1.36 ERA, 1.00 WHIP, 25.6% strikeout rate, and a .250 wOBA that was one of the best marks among starters. His two starts this season haven't been as stellar, as he has a 5.87 ERA and a .348 xwOBA over 7 2/3 innings pitched. The season is still young, and Suarez's second start was much better than his first, so what can fantasy managers expect from him this season?

Suarez relied on a sinker (45.5% usage), changeup (24.1% usage), four-seam fastball (22.6% usage), and slider (7.8% usage) in 2021, but he did very well with his limited pitch arsenal. His batted-ball profile was great overall; he had an elite 86.7 MPH average exit velocity, 31.1% hard-hit rate, and 4.4-degree average launch angle. Are there any signs so far that this pitch arsenal and batted-ball profile from 2021 may not be repeatable?

Again, it is very early in the season, so everything should be taken with a grain of salt. Suarez's first start was a mess, as he allowed three runs over just 2 2/3 IP against the Mets, a tougher matchup. However, he looked to be more in form in his second start, earning the win at the Marlins by pitching five innings of two-run ball with three walks and four strikeouts. His four walks over 7 2/3 IP may be something to keep an eye on, but his pitch mix and velocities have been similar to his 2021 metrics.

I don't think anyone expected Suarez to replicate his 2021 season, as it simply is not realistic to maintain such stellar marks over the course of an entire season. That being said, many fantasy managers are excited to have him on their rosters. His start has not been ideal, but there aren't any red flags to this point. His 2022 xwOBA may be one of baseball's highest early on, but I am going to trust his 2021 mark and expect to see him settle in over his next couple of starts.

Carlos Rodon, San Francisco Giants

2021 xwOBA: .253

2022 Stats: (1-0, 1.50 ERA, .195 xwOBA)

Carlos Rodon is a guy who fantasy managers have had high hopes for for years, but had never been able to string together spans of healthy, strong performances. His 2021 season with the White Sox finally delivered, as he went 13-5 with a 2.37 ERA, 0.96 WHIP, 34.6% strikeout rate, and a .253 xwOBA that was 14th-best among qualified pitchers (including relievers). He was rewarded with an All-Star appearance and a two-year, $44 million contract from the Giants in the offseason. He has looked just as good through his first two starts, posting a 1.50 ERA with 21 strikeouts over 12 innings pitched. How has Rodon found his success?   

Rodon's pitching approach is actually fairly straightforward. He has relied on a lively fastball and a sweeping slider throughout his career but had struggled with command. Health was clearly a difference-maker for Rodon in 2021 regarding his pitches. His fastball velocity was a mediocre 91.4 MPH in 2019 and 92.8 MPH in 2020, but he was able to up that to 95.4 MPH in 2021 and has averaged an impressive 97.1 MPH to start 2022. Consequently, he was able to achieve a 13.8% swinging-strike rate with his fastball in 2021. The story is similar for his slider. He averaged 83.8 MPH with the pitch in 2019 and 83.4 MPH in 2020, but upped that to 85.8 MPH in 2021 and 85.6 MPH in 2022. In addition to the velocity, Rodon was able to generate much more vertical and horizontal movement with the pitch and generated a 17.5% swinging-strike rate in 2021.

Rodon had his peak arsenal at his disposal for 2021, but what did he do with them? His 2.44 BB/9 rate in 2021 and 3.00 BB/9 rate in 2022 compared to his career 3.58 mark indicates that he located his pitches better. He has kept his fastball in the top of the zone and has busted his slider inside to right-handed hitters. His batted-ball profile has been ok, but his low contact rates more than make up for that.

It looks like a healthy Rodon is the fantasy pitcher managers had always envisioned, and his 2022 season has looked exactly the same as his successful 2021 season. With his swing-and-miss stuff in the friendly confines of Oracle Park, the only reason that Rodon could be derailed from a top fantasy season is an injury. His underlying metrics suggest that he can be a serious fantasy contributor even if he only pitched the 130+ innings he logged in 2021.

xwOBA Duds

All stats are current as of Sunday, April 17, 2022.

Mitch Keller, Pittsburgh Pirates

2021 xwOBA: .360

2022 Stats: (0-2, 9.39 ERA, .313 xwOBA)

Mitch Keller is another pitcher who fantasy managers were excited about several seasons ago, but he has yet to provide much value, even in dynasty leagues. His 2021 season yielded a 5-11 record with a 6.17 ERA, 1.79 WHIP, 19.6% strikeout rate, and a bloated .360 xwOBA. He showcased higher velocity on his fastball this spring but has a 9.39 ERA across his first two starts this season. It is too early to come to solid conclusions, but should fantasy managers hold out hope that Keller can turn things around this season?    

The 26-year-old has shown a fastball velocity boost in his first two starts at 96.3 MPH, compared to 93.8 MPH in 2021. The issue is that the added velocity has not translated to success. Keller kept the pitch in the middle of the plate too often in 2021, leading to an inflated .313 batting average against. He has done the same so far in 2022, so despite the extra velocity, he has given up a .400 batting average against his fastball. Further, his pitch mix does not appear to be enough to keep hitters off-balance. He does have a slider, curveball, and changeup that he has mixed in over the past several seasons, but he relies heavily on his fastball and only his changeup has been successful to start this season.

Part of the strategy of fantasy sports is to identify players who could return more value than the consensus believes in. Keller could be one of those guys, given his prospect pedigree and the improved fastball velocity. However, Keller does not appear to be a different pitcher than who he was in 2021. He relies too much on his fastball, which he has not located well. Further, his off-speed pitches did not fool hitters in 2021 and mostly have not fooled them in 2022. I think we have a true fantasy dud on our hands in this case.

Tarik Skubal, Detroit Tigers

2021 xwOBA: .357

2022 Stats: (0-1, 3.72 ERA, .339 xwOBA)

Tarik Skubal is yet another intriguing fantasy pitcher coming into his second full season in 2022. His rookie season numbers were ok overall, as he went 8-12 with a 4.34 ERA, 1.26 WHIP, and 25.9% strikeout rate over 149 1/3 IP. However, his .357 xwOBA was one of the highest in baseball. He has produced similar results through his first two starts in 2022, compiling a 3.72 ERA, 1.24 WHIP, 23.8% strikeout rate, and .339 xwOBA. Is his current xwOBA a sign of future mediocrity?

Unlike Keller, Skubal has at least four pitches that he uses at least 10% of the time. He got subpar results from his four-seam fastball in 2021 (42.8% usage), but he got strong results from his slider (22.8% usage), sinker (12.9% usage), changeup (12.1% usage), and curveball (6.8% usage). The main culprit behind Skubal's poor 2021 xwOBA was likely his batted-ball profile; he gave up a poor 90.1 MPH average exit velocity, 45.1% hard-hit rate, and 14.1-degree average launch angle. His small sample in 2022 seems to be a step in the right direction. His average exit velocity and hard-hit rate are currently in the bottom 31st and 50th percentiles in baseball, respectively, but his average launch angle is down to a manageable 7.3 degrees. His 2.68 SIERA supports the idea that his batted-ball profile has improved thus far.

It remains to be seen what the ceiling could be for the 25-year-old, but he has a good pitch mix and can generate some strikeouts. He should be at the least a useful back-end fantasy starter if he can continue to keep the ball relatively on the ground while avoiding frequent hard contact. Here is an example of a dud by the metric, but a potentially useful fantasy pitcher overall.

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