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Welcome back to RotoBaller’s pitchers advanced stats and StatCast studs and duds article series! Each week we will select an advanced stat, choose two studs and two duds, and analyze what those stats could mean for future fantasy output. I wrote an article about SIERA in week 6 and this week am going to build on that by comparing pitchers' ERAs to their SIERAs.
SIERA quantifies a pitcher's performance by trying to eliminate factors the pitcher can't control on their own. FIP is a stat that also attempts to do this, but unlike FIP, SIERA considers balls in play and adjusts for the type of ball in play. The formula can be found here for those who want to get into the nitty gritty.
SIERA is a better indicator of a pitcher's performance than ERA and can help predict future success or failure compared to a pitcher’s current ERA. This will be a great way to identify potential buy-low and sell-high candidates at a time when every roster move is that much more impactful, so let’s get going!
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ERA-SIERA Studs
All stats current as of the day of 6/24/19
Eduardo Rodriguez - Boston Red Sox
(8-4, 4.71 ERA, 1.36 WHIP, 3.98 SIERA)
Our first ERA-SIERA stud is one who has shown fantasy promise but has been inconsistent this season. Eduardo Rodriguez has shown that he can post high strikeout numbers but has also shown a lack of command and a propensity for getting injured. His 4.71 ERA and 1.36 WHIP through his first 86 innings pitched this season are certainly not encouraging. However, the difference between his ERA and SIERA suggest that he has been pitching better than his peripherals indicate. Could Rodriguez be the buy-low candidate worth investigating?
Rodriguez has a lot going on under the hood that suggests he should be performing better than he has been. First, he has done a great job at limiting hard contact (86.2-MPH average exit velocity, 29.1% hard-hit rate, 10.4-degree launch angle) yet has gotten unlucky on balls in play. Rodriguez has an inflated BABIP (.338 compared to a .299 career mark) and a 1.36 WHIP despite having a respectable 6.8% walk rate. This is all reflected in his relatively-lower SIERA.
Additionally, Rodriguez has still displayed the main attribute that fantasy players have always liked about him, his strikeout potential. E-Rod has a 25.2% K rate to this point and has at least a 10% swinging-strike rate on three of his four main pitches, the highest being on his devastating changeup at 18.6%. There are a lot of encouraging signs behind his poor numbers and I would try to buy low on him. Once regression starts to benefit him, Rodriguez could be a strong piece for a contending fantasy roster.
German Marquez - Colorado Rockies
(7-3, 4.32 ERA, 1.19 WHIP, 3.69 SIERA)
Our second ERA-SIERA stud made his mark on fantasy radars in the second half of last season but hasn't made the same impact in 2019. German Marquez has shown that he has the strikeout numbers and command to be an intriguing option even in Coors Field, but he has gotten hit hard this season. Despite this, his 3.69 SIERA is much better than his 4.32 ERA. What should fantasy players make of Marquez's value for the rest of the season?
Let's first look at Marquez's batted-ball profile. The bad thing is that he has indeed gotten hit hard; Marquez's average exit velocity (90.3 MPH) and hard-hit rate (43.5%) are both in the bottom 10 percent of the league. This does not bode well, especially in the thin air at his home park. The good thing is that he has kept the ball on the ground. Marquez's 5.5-degree launch angle is saving him, as a hard-hit ground ball is an outcome that any pitcher will take.
The one is a bit of a tough case. Marquez's command seems to be fine and his strikeouts are still there (24.3% K rate), but his hard-hit rate is concerning. His SIERA suggests that his batted-ball profile is fine given his launch angle, but the fact that he is at Coors Field still makes me nervous. Marquez is worth a buy-low offer given his upside, but I wouldn't offer up too much for him at this time.
SIERA Duds
All stats current as of the day of 6/24/19
Mike Minor - Texas Rangers
(7-4, 2.52 ERA, 1.15 WHIP, 4.27 SIERA)
Our first ERA-SIERA dud is a veteran who is putting forth an excellent season to this point. Mike Minor has performed extremely well in 2019 despite pitching his home games in hitter-friendly Globe Life Park, posting a 7-4 record with a 2.52 ERA, 1.15 WHIP, and a 24.6% K rate through 103 2/3 IP. However, a much . uglier 4.27 SIERA lurks under his shiny peripherals. Should fantasy owners look to sell high on Minor while they have the chance?
Several things stand out for me, and all of them actually look good. First, Minor has done a great job of limiting hard contact this season; his average exit velocity (86.3 MPH) and hard-hit rate (31.6%) are both in the top-17th percent of the league. Further, all of his expected stats (batting average, slugging percentage, weighted on-base average) are in at least the 64th percentile of the league, so his batted-ball profile is translating into expected success in other places besides his SIERA.
While I think it is reasonable to expect some negative regression for Minor, his underlying stats suggest that his success is legitimate. His SIERA suggests that he has been outperforming, yet his batted-ball profile is solid. With a decent K rate to go with everything else, I like Minor as a surprise middle-of-the-rotation piece for fantasy players. Don't be afraid of his SIERA; even if his ERA regresses, he should still be a useful fantasy option!
Julio Teheran - Atlanta Braves
(5-5, 3.40 ERA, 1.26 WHIP, 5.09 SIERA)
Our second ERA-SIERA dud has had a great start to the season, going 5-5 with a 3.40 ERA, 1.26 WHIP, and 21.2% K rate. Julio Teheran has found success to this point despite having an ugly 5.09 SIERA. He has had an up-and-down fantasy career, so what should fantasy players expect of him with his conflicting numbers?
Teheran has a bunch of things going on under the hood that make me question his peripheral stats. First, his command has been an issue throughout the season. His 1.26 WHIP isn't awful, but his 11.5% walk rate is concerning. He doesn't have overpowering stuff (his fastball sits at just 90 MPH on average), so he needs to have strong control to be successful.
Second, Teheran's batted-ball profile isn't that bad (87.5-MPH average exit velocity, 35.8% hard-hit rate, 12.4-degree launch angle), but he has been getting too much of the plate with his fastballs. This fact combined with his BABIP that is lower than his career mark (.245 vs .267) make me worried that Teheran is walking a fine line and is close to being on the wrong side of it.
Overall, I would consider Teheran to be a bonafide dud waiting to happen. He has never been that exciting of a player and his underlying stats suggest that he has been overachieving significantly to this point. He is a strong sell-high candidate going into the second half of the season.
