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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. The next stat we will use is one that utilizes exit velocity and launch angle to predict how much damage pitchers allow on batted balls, expected slugging percentage (xSLG).
To calculate xSLG, every batted ball is given a single, double, triple and home run probability based on the results of comparable batted balls. The probabilities for an individual batted ball are then plugged into the SLG formula (1B + 2Bx2 + 3Bx3 + HRx4)/AB to get the xSLG for that batted ball.
xSLG is more indicative of a player's skill than regular SLG because expected outcomes of batted balls are more likely to occur over the course of a season. xSLG removes defense from the equation, which makes sense because pitchers cannot influence what happens to a batted ball once it is put into play. Given its predictive nature, xSLG will be an interesting tool to identify potential fantasy steals and guys to avoid.
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xSLG Studs
All stats current as of 5/13/19 and courtesy of BaseballSavant.com
For reference, the league average SLG and xSLG for pitchers is .417 and .414, respectively.
Jerad Eickhoff - Philadelphia Phillies
2-1, 1.50 ERA, 0.97 WHIP, .287 xSLG
Our first xSLG stud had an impressive 2016 fantasy season but was mediocre in 2017 and was hurt in 2018. Jerad Eickhoff has gotten off to a great start in 2019, posting a sterling 1.50 ERA over 30 IP and is in the 90th percentile for all of his expected statistics (xBA, xSLG, xwOBA). Has the 28-year-old returned to his 2016 form and are his stats legit?
Eickhoff does not have overpowering stuff so he has to rely on mixing his pitches and good location to be successful. He has never thrown hard and his velocity is down across the board compared to his 2017 numbers (his fastball has averaged just 89.7 MPH in 2019). However, all of his pitches have significantly more spin to them, which allows him to pitch deceptively. He is also mixing his pitches well, throwing his fastball (37.9%), curveball (31.4%), and slider (30.5%) almost evenly. While Eickhoff's 16.3-degree launch angle isn't the best, he has been able to keep hitters off-balance and has limited hard contact (average exit velocity 87 MPH, 31.9% hard-hit rate).
Eickhoff has managed to both avoid damaging contact and also rack up strikeouts. His 27.2% strikeout rate and 12.1% swinging-strike rate are both better than his 2017 marks of 20.5% and 8.8%. The only couple of worrisome stats for Eickhoff are his BABIP (.250 vs .295 career) and his SIERA (3.96), which both concern batted balls and both suggest that some regression could come for the worse.
Overall, Eickhoff presents a rather unique pitching profile that has worked well to this point. His expected stats are strong across the board but his launch angle, BABIP, and SIERA suggest that he may not be as good as he has shown. I would like to see a bit more from Eickhoff before completely buying into him.
Julio Urias - Los Angeles Dodgers
2-2, 3.18 ERA, 1.09 WHIP, .321 xSLG
Our second xSLG stud has been surrounded by fantasy buzz since 2016 and is only 22 years old. Julio Urias has shown that he can compete at the big-league level despite his age, whether it be as a starter or coming out of the Dodgers' bullpen. Even if he is not starting, Urias has provided solid numbers in roto categories, so he can still be fantasy relevant. Let's take a further look into Urias' advanced metrics to see how he has found success.
In short, Urias is a Statcast freak. He is in at least the 80th-percentile for fastball velocity (94.8 MPH), fastball spin (2,481 revolutions per minute), curveball spin (2,766 revolutions per minute), exit velocity (85.7 MPH), hard-hit rate (27.6%), and expected stats. He relies heavily on his fastball (58.6% usage), which, to be fair, is quite a good pitch, but he also has a strong secondary arsenal of changeup, slider, and curve. Aside from avoiding damaging contact, Urias has been able to post solid strikeout numbers with a 26.7% strikeout rate and a 13.6% swinging-strike rate. His 3.68 SIERA, while higher than his ERA, is still solid.
The only thing to possibly worry about for Urias is his playing time. He is still young, so an innings cap is always a possibility; plus, the Dodgers often switch around their pitching staff roles. Urias has compiled a respectable 28 1/3 IP so far this season and will get utilized any way possible if he continues to pitch this well. Owned at just 32%, Urias is certainly worth a spot on fantasy players' benches as a stash.
xSLG Duds
All stats current as of 5/13/19 and courtesy of BaseballSavant.com
For reference, the league average SLG and xSLG for pitchers is .417 and .414, respectively.
Jake Arrieta - Philadelphia Phillies
4-3, 3.78 ERA, 1.32 WHIP, .487 xSLG
This pitcher used to be a flamethrower and a major fantasy strikeout asset but seems to be shifting his style as he gets older. Jake Arrieta's 92.6-MPH sinker is not the 95 MPH it used to be, but he has managed to find success this season by pitching more to contact (we'll dive into this in a minute). However, his xSLG of .487 is concerning, given his shift in approach and the fact that his expected value is quite a bit higher than his .400 SLG. What should fantasy owners make of Arrieta's xSLG?
Arrieta has made adjustments to his pitch arsenal in order to remain effective. He has switched to a duo of sinker and changeup (a classic strategy to keep hitters off balance) over the power slider he used to rely on. This tactic has worked for Arrieta thus far; he is definitely pitching to contact (82.4% contact rate), but he is keeping the ball the ball down in the zone and balls in play on the ground (8.8-degree average launch angle). Arrieta will need to continue to keep the ball on the ground because he is giving up a lot of hard contact (average exit velocity 90.2 MPH, hard-hit rate 42.1%).
This is the batted-ball conundrum for Arrieta; he is seeking out contact and is getting hit hard but in preferable locations. His .400 SLG is actually below the league average, yet his xSLG suggests he should be giving up more damaging hits. His SIERA still sits at 4.58, but he has still managed to provide decent fantasy value. I think that Arrieta can continue to be a middle-of-the-rotation fantasy starter as long as he keeps the ball down.
Chris Archer - Pittsburgh Pirates
1-2, 4.33 ERA, 1.30 WHIP, .486 xSLG
Our second xSLG dud has been a disappointment fantasy-wise over the past several seasons. Chris Archer has been a reliable workhorse with high strikeout upside but has also shown a lack of command and an average ERA. He has gotten off to a mediocre start to 2019 and should soon be returning to action soon after being sidelined with right thumb inflammation. With a less-than-encouraging start and an xSLG that is higher than his .414 SLG, should fantasy owners be thinking of trying to get rid of Archer?
Two things stand out with regards to Archer's batted-ball profile. The first is that he has lost velocity on his fastball. Archer's fastball has sat at 93.1 MPH this season as opposed to the 96 MPH of old. This may improve some if his thumb is back to 100% but it is worrying, as Archer's fantasy value has been in his velocity and strikeouts. He has actually thrown his slider slightly more than his fastball this season (34.5% usage vs 32.8%), a trend that he started last season.
The second thing that stands out is Archer's continuing lack of command. His 1.30 WHIP is not great and his walk rate is currently too high at 10.6%. Archer hasn't necessarily gotten hit hard (86.7-MPH exit velocity, 33.8% hard-hit rate), but his 16.8-degree launch angle leaves something to be desired. Further, the less command he has, the more likely he is to throw hittable pitches, which is certainly suggested by his high xSLG.
Archer has been declining in fantasy value since 2016 so his production in 2019, while frustrating, shouldn't be all that surprising. His velocity is down, his command still isn't great, and, consequently, he hasn't performed all that well and is expected to perform worse in terms of allowing big hits. He could still be a back-end rotation guy if he can stay healthy and provide a decent volume of work, but that seems to be his ceiling at the moment. If he can return from the IL and have a good start or two, I would try selling high on him based on his name.
