Pitcher Advanced Metrics Studs and Duds - xERA For Week 10

June 13, 2022

Connelly examines fantasy baseball pitcher risers and fallers, whose xERA could make them adds, drops or trade targets for Week 10.

Welcome back to RotoBaller’s Statcast pitcher Studs and Duds article series! Each week, I will select one advanced metric, choose two pitchers with strong values and two with poor values, and analyze what those values may mean for future performance. There are many ERA skill indicator metrics that fantasy managers can use to understand how pitchers are performing beyond their peripherals. SIERA is my favorite (I wrote about it in Week 7), but this week I will write about a metric that is fairly new to me: expected ERA (xERA).

xERA is a 1:1 translation of Expected Weighted On-Base Average (xwOBA), converted to the ERA scale. Like SIERA, xwOBA takes into account the amount of contact and the quality of that contact a pitcher allows in an attempt to credit them for the moment of contact. Unlike SIERA, xwOBA/xERA does not factor in ballpark conditions.

SIERA and xERA may be similar, but it will be interesting to investigate what fantasy managers can glean specifically from xERA. We are over two months into the season but obviously have plenty of time to go, so the earlier fantasy managers can identify over and underachievers the earlier they can take advantage of buying low or selling high. With that, let's dive into some xERA Studs and Duds!

xERA Studs for Fantasy Baseball

All stats are current as of Sunday morning, June 12, 2022.

Martin Perez, Texas Rangers
4-2, 2.18 ERA, 1.10 WHIP, 2.57 xERA

Martin Perez is a player that baseball fans will certainly be aware of, but perhaps not fantasy managers. The 31-year-old has been a spot streamer at best throughout his fantasy career and has a 4.55 ERA to show for it. 2022 has been quite a difference, as he has compiled a pristine 2.18 ERA with a 2.57 ERA that is fifth-best among qualified starters. Is Perez a potential sell-high candidate or a fantasy diamond in the rough?

Perez presents a relatively mixed bag when taking a closer look under the hood. He is not an overpowering pitcher and relies mainly on a sinker (36.7% usage), changeup (25.6% usage), and cutter (24.3% usage). His sinker averages 92.5 MPH and his cutter averages 89.6 MPH, so his low 20.0% strikeout rate and high 80.5% contact rate make sense. He has located his sinker and changeup well while scattering his cutter around the zone, which has appeared to have kept hitters off-balance. That being said, his batted-ball profile is decent but not excellent. His average exit velocity and hard-hit rate are in the 53rd and 64th percentiles of baseball, respectively, but his 7.5-degree average launch angle seems high for a pitcher who pitches to contact and relies on a sinker primarily.

Perez has obviously gotten superb results so far this season and has done some things well, but there isn't overwhelmingly compelling evidence that his success will be sustainable over the course of the season. His xERA is almost a run higher than his ERA (it is unreasonable for any starting pitcher to maintain such a low ERA), but his SIERA is about a run higher than his xERA. I consider Perez to be a sell-high candidate given his current underlying numbers as well as his career track record.

Luis Severino, New York Yankees
4-1, 2.80 ERA, 1.03 WHIP, 2.57 xERA

Fantasy managers have definitely been aware of Luis Severino in the past as a high-end starting option, although he had not been able to pitch in a meaningful capacity since 2018 due to injuries. The 28-year-old appears healthy once again and is putting up numbers of old, compiling a 2.80 ERA, 1.03 WHIP, 28.9% strikeout rate, and a 2.57 xERA that is fifth-best among qualified starters through his first 11 starts and 61 innings pitched. Do fantasy managers have anything to worry about in terms of Severino's performance?

Unlike Perez, Severino has a lot of supporting underlying metrics. He does have the benefit of a strong pitch arsenal. He hasn't thrown his four-seam fastball quite as hard as he did in 2018, but he has still averaged 96.3 MPH with above-average movement. He has also been able to effectively incorporate a cutter into his pith mix to save himself from throwing so many sliders. His slider is clearly his best swing-and-miss pitch with a 21.3% swinging-strike rate, but his 90-MPH cutter has a ton of horizontal movement on it and has generated a respectable 13% swinging-strike rate. His batted-ball profile has been middle-of-the-road, but his strong stuff more than makes up for it.

All in all, the only potential concerns about Severino are injury-related. He has pitched very well, has a track record of success, and has an xERA and 3.06 SIERA that are all much closer to his actual ERA than Perez's. I think fantasy managers can expect high-level contributions from Severino for the rest of the season.

xERA Duds for Fantasy Baseball

All stats are current as of Sunday morning, June 12, 2022.

Marco Gonzales, Seattle Mariners
3-6, 3.63 ERA, 1.37 WHIP, 4.95 xERA

I have brought up this phenomenon before, but some pitchers always seem to out-perform their underlying numbers. Marco Gonzales is one of those pitchers. The 30-year-old has put together a respectable 3.63 ERA over 62 IP despite a 1.37 WHIP, 14.1% strikeout rate, and 4.95 xERA. Fantasy managers seem to be savvy to this, as he is currently rostered in just 23 percent of leagues. Could Gonzales be worth a roster spot in deep leagues given his proclivity to outperform?

While he has managed to find success despite his underlying metrics for some time now, I would still be very wary of Gonzales. His underlying metrics are not good, as evidenced by his xERA. For instance, he has allowed league-average hard contact but has a 14.1-degree launch angle. He does have the benefit of pitching in a pitcher-friendly park, but he does not throw hard and peculiarly pitches up in the zone with his sinker and cutter. As such, I would expect that combination to eventually turn into damaging contact. His only pitch with strong expected metrics is his changeup, which he has been able to keep in the bottom of the zone. He does throw the pitch often at 32.4%, but I have difficulty trusting a starter whose fastballs do not generate strong results.

Gonzales has managed a sub-4.00 ERA since 2019 while never really having stellar metrics under the hood. This is an impressive track record on its own, but it still is not enough for me to buy into him unless I was in deeper leagues and dealing with pitching injuries in my rotation. The underlying metrics do tend to catch up to players, and Gonzales' high xERA makes me nervous.

Robbie Ray, Seattle Mariners
5-6, 4.52 ERA, 1.25 WHIP, 4.29 xERA

Robbie Ray has had an inconsistent fantasy career, but 2021 was the brightest spot so far, as he took home the American League Cy Young award. Many fantasy managers bought into him for 2022, but have been disappointed, as Ray has gone 5-6 with a 4.52 ERA, 1.25 WHIP, and a pedestrian 4.29 xERA. Now two months into the season, is there hope that he can pitch more like he did last season?

The culprit behind Ray's performance seems to be his batted-ball profile. The walks, which have been an issue for Ray in the past, have been held in check at 3.24 BB/9. His strikeout rate is down some at 25.8%, but his swinging-strike rate is at a career-high 15.7% while his contact rate is at a respectable 70.2%. In sum, everything looks good, until you turn to the batted-ball profile. Ray's exit velocity and hard-hit rate are in the seventh and 27th percent of baseball, respectively, and his 15.9-degree launch angle is a recipe for damaging contact. It is worth noting that he has seen a decrease of over one MPH on both his fastball and slider (his two main pitches).

All in all, there is not enough here for me to think that Ray is doomed. He has seen a slight drop in velocity and strikeouts, but has been getting more swings and misses than ever and has not had his walks get out of hand. His batted-ball profile is lackluster but is actually not all that different from his career marks. I would expect to see more strikeouts as the season progresses and overall results that are more similar to what he did last season due to regression. As such, Ray is a buy-low candidate for me.

More Sabermetrics and Statcast Analysis