Toronto Blue Jays’ Aaron Loup might be hitting batters, but batters aren’t hitting him


It might surprise you to learn that Toronto Blue Jays reliever, Aaron Loup, has been more effective than we thought


Aaron Loup is not one of the more beloved Toronto Blue Jays. He may not even be a liked or tolerated Blue Jay for many fans. But he is a Blue Jay, so I try to give him the benefit of the doubt.


Here are some facts about Aaron Loup’s 2017 season:

  • He has a low ERA (2.76 vs. 4.06 for the average MLB reliever)
  • He has a high WHIP (1.53 vs. 1.32)
  • He has a reverse batting average split (righties are hitting .238 against him, while lefties are hitting .261)
  • He has a high left-on-base (LOB)% (79.7% vs. 72.7%)


The first fact is positive. Pitchers that give up few earned runs tend to be doing their job well.


The second and third facts are negative. A high WHIP suggests that a pitcher is allowing a lot of baserunners. A reverse split might not be good for a lefty specialist (like Loup), who would want to be particularly good at getting out lefties.


The fourth fact is a little bit of both. Looking backward, a high LOB% indicates that a pitcher has been stranding runs, which is a good thing. Looking forward, a high LOB% (particularly one above the pitcher’s career average) suggests that the pitcher has benefited from good luck and probably “should have” given up more runs than he did (stranding an unusually high number of runners allowed him to keep his ERA artificially low).


Put together, someone might conclude that while Aaron Loup has managed to limit runs against (low ERA), he’s been ineffective at limiting baserunners (high WHIP), especially lefties (reverse splits), and has benefited from good luck (high LOB%).


In 2017, you are tying both hands behind your back if you are making sweeping conclusions on baseball players based on ERA, WHIP, LOB% and batting average splits alone.


The questions I want answered will help me figure out whether or not Aaron Loup has done his job as a left-handed reliever effectively.


Is his WHIP really that much above-average?

Technically, yes. But WHIP is based in part on batting average (the “H”), which is a poor indicator of the quality of contact a pitcher is giving up. A better indicator is xBA, Statcast’s expected batting average. It gives batters partial credit for each batted ball based on its hit probability. That way, a batter whose well-hit line drive is caught by a great defensive play gets more credit than a batter who got to first on a (completely unintentional) swinging bunt.


While Loup’s BA is .250, his xBA is .177! So, while 16 of the 64 at-bats hitters have had against Loup this year have resulted in hits, his “expected number of hits against” is only 11.5. If we plug that into the WHIP calculation, we get a 1.26, better than the average MLB reliever (1.32).


Is the high LOB% concerning going forward?

Not really. If we replace hits with expected hits (derived from xBA again) in the LOB% calculation, Loup’s LOB% drops from 79.7% to 75.8%, pretty close to his career mark (74.9%).


Does he really have reverse splits?

Technically, yes. But his xBA splits are normal. While righties have only been able to produce a .179 xBA against him, lefties have been limited to a .171 xBA. The same holds for his xwOBA splits (.273 vs. LHH, .278 vs. RHH).


So, is Loup a bonafide LOOGY?

Yes, as long as you believe that the Statcast expected stats (xBA and xwOBA) are better predictors of future talent than their regular counterparts (BA and wOBA).


Among 65 lefty relievers with 10+ AB against lefty batters in 2017, Loup ranks:

  • 49th in BA (.273) and 34th in wOBA (.245)
  • 16th in xBA (.171) and 14th in xwOBA (.162).


All in all, is Aaron Loup worth keeping or not?

He is.


Besides being an above-average LOOGY (in terms of process, if not results), he’s performing better overall than he had over the last two seasons. His total walk rate is up and his strikeout rate is down, but the most significant change is his improved xwOBA (and wOBA) on batted balls. This implies that he has been generating much weaker contact than in the past. Put together, Loup has posted 2017 xwOBA and wOBA that surpass his 2015 and 2016 marks. So, while he is doing two parts of his job worse (allowing more walks and striking out fewer batters), he is doing one part of his job (limiting high-quality contact) so much better that we can say that he has improved overall.



Let’s compare these same stats to MLB relievers overall. Again, on the one hand, he is posting sub-par strikeout and total walk rates so far this year. That’s bad. On the other hand, he is giving up some of the weakest contact in the majors (better than average xwOBA and wOBA on batted balls). That’s good. When the strikeouts, walks and batted balls are all combined together, Loup produces a better than average xwOBA. That’s good. Unfortunately, his wOBA is 44 points higher than his xwOBA (41st biggest difference in the majors). That’s bad luck.



I think that gets us to the bottom of the story. For a long time, we assumed that bad outcomes meant bad performance. Now, we can get a better idea of whether the issue is bad performance or bad luck. Let’s not waste that opportunity. Let’s try not to dump on guys every single time they have a stretch of bad luck, especially when we have good evidence to show that the player is actually doing a lot right on their end. Certainly enough right to succeed.


Aaron Loup is earning $1.1 million this year. The average relief pitcher in the MLB will earn about $1.6 million. The Jays are paying Loup a below average salary, yet are receiving an above-average performance (by overall xwOBA). Sure, he hits a disproportionate number of batters. But, way more importantly, those batters haven’t been hitting him this year.




*Featured Image Credit: Keith Allison UNDER CC BY-SA 2.0








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