The Astros Built a Phenomenal Bullpen

As you’ve probably heard before, there’s not a lot of rooting in this job. Not, at least, rooting of the conventional sort, for a particular team against a particular opponent. What there’s more of is rooting for particular stories, or particular trends. That’s where I found myself earlier — rooting for the Astros bullpen against the Rangers on Thursday, because I knew I wanted to write about it. It was going well, too, until Rougned Odor went deep off of Scott Feldman in the eighth. The Astros never rallied. Still, the bullpen yielded just the one run in more than four innings of work. It did its job, which makes this a decent time to point out it’s rather consistently been doing its job.

The offseason past was the offseason of relievers, and upon its completion, people couldn’t wait to see what the Yankees had assembled in action. The Astros by no means sat the offseason out, but there hasn’t been so much talk about them, what with the disappointing start. And if you think about the Astros bullpen, you might immediately think of the early struggles from Ken Giles. You might think about Luke Gregerson losing his closing gig. Not everything has gone smoothly, which makes it all the more remarkable that the Astros bullpen has been so dominant.

It has been dominant. I don’t think that’s overstating things. The Astros have leaned on it, too, the starting rotation having been through some rough patches. The Yankees get all the attention for being so top-heavy, but the Astros have been strong top to bottom, and this table conveys all the right ideas. Here’s where the Astros bullpen stands in an MLB context, as of this writing:

2016 Astros Bullpen
Stat MLB Rank
K% 2
BB% 1
K-BB% 2
ERA- 5
FIP- 1
xFIP- 1
Shutdowns 1

The worst rank is in adjusted ERA, and you could argue that’s the most important rank. On the other hand, WPA is probably even more important as long as we’re looking back, and besides, ranking fifth in baseball in adjusted ERA is pretty terrific. You know how all these numbers work. You know you can’t ignore ERA, but you also know to trust FIP. The Astros are first in adjusted FIP. In strikeout rate, and in strikeout rate minus walk rate, they’re behind only the Yankees. They lead in shutdowns by a mile.

The Yankees have the star power. The Orioles have the history. The Royals have the reputation. The Astros bullpen is more anonymous, and of course that bullpen melted down before a national audience last October. You don’t think of the Astros bullpen as being so good, but the numbers are right there, and we can take this beyond just 2016. Why don’t we go back to 2002? Since then, this Astros bullpen would still rank second in K-BB%. It would rank first in walk rate, by a full percentage point. It would rank second in adjusted FIP, and it would rank second in adjusted xFIP. This is out of 450 team-seasons. Only the 2003 Dodgers were clearly better, by those last two statistics. And the Astros are close.

No, not all the Astros have pitched like they’ve wanted, but the bullpen really has been deep. Nine Astros relievers have thrown at least 10 innings. Here’s a plot of all the relievers with 10+ innings, showing their walk rates and their strikeout rates:


The really good relievers are mostly toward the upper left. That’s where you find literally all of the Astros included. The league-average K-BB% for a reliever this season is about 14%. The worst K-BB% in the Astros bullpen is 16%, which ranks Pat Neshek in the 61st percentile. That’s the worst, and this is out of nine guys, which is too many guys for a bullpen to have at once. There’s flexibility and depth, and the Astros are thinking about turning one or two of their current relievers into starters.

Things haven’t gone perfectly for Giles. Things haven’t gone perfectly for Gregerson. They’ll both be all right, I assume, but the Astros have really been driven by Michael Feliz and Will Harris. Combined, they have 70 strikeouts and 10 walks, with a 2.92 WPA. Harris was quietly good last year after arriving on waivers from the Diamondbacks; since the start of 2015, he’s allowed a .237 OBP. He seems to have gotten even better. Last year, Feliz was infrequently discussed. This year he’s moved into the bullpen and taken off. Since the start of May, he’s been good for two walks and 33 whiffs, with a .222 OPS that is not a typo. Harris has stepped up and Feliz has emerged, and when you add those factors to what was already a quality unit, you get something sensational.

Could be, a slump is on the way. Or, perhaps, an injury. Or, perhaps, a promotion, where Feliz goes to the rotation and the bullpen loses that arm. They might instead promote Chris Devenski to the rotation, and by the way, he’s been good, too. We are still just two months in, and there are six months in a whole year, and just last summer we saw a reliable Astros bullpen come apart at the very wrong time. But you already know it’s too soon to arrive at historical conclusions. That doesn’t mean we can’t examine performances, and when you examine the performance of the Astros relievers, they’re right there with the best we’ve seen in a while. The back of the Yankees bullpen has the sex appeal. The Astros, I’m sure, are happy to settle for the statistics.

Jeff made Lookout Landing a thing, but he does not still write there about the Mariners. He does write here, sometimes about the Mariners, but usually not.

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6 years ago

Using just the described factors from the top of this post, I calculated the z-scores for each for each team… and averaged them together [sure, some/many/most might say not to do that, but I’m a rebel :)]

Astros +1.8
Yankees +1.4
Nationals +0.8
Orioles +0.8
Royals +0.7

Angels -0.7
Padresd -0.7
D’Backs -0.8
Pirates -1.0
Reds -2.6

Might be more notable how historically terrible a bullpen the Reds have created than how great the Astros’ has been. The gap from the Reds at #30 to the Pirates at #29 is the same as 7th to 29th! or 3rd to 28h. Astounding.

Given a presumably high correlation between K% and BB% to K-BB%, ditch the first two and the gap from 29th to 30th is now the same as 4th to 29th

6 years ago
Reply to  rosen380

Terrible bullpens are the new Tankball