The Brewers Bullpen, will it hold up?

The Brewers bullpen has been incredible. They have the highest fWAR, the second highest K/9, and the third lowest ERA. But the one stat that most Brewers fans are looking at, is the 98.1 innings pitched. It may surprise some that this is only the fourth highest total in baseball. Even so, it is a large number that has certainly helped the Brewers to their stellar 16-9 start, but foreshadows a possible crisis in store when the bullpen runs out of gas.

Which brings me to the question many Brewers fans are asking: will the bullpen hold up?

The only real way to know is to watch the season play out. Counsell is using his bullpen differently than the traditional manager of the past five to ten years. He is using more multiple inning outings, not relying on a sole closer, not bringing in guys for just one hitter, not using the same pitcher on back to back nights etc.

On the other hand, if we want to make any sort of inference about whether or not this Brewers start is unstainable, we need to know if the bullpen use will work. The only way I know how to do that is to look backwards and compare the Brewers bullpen to the bullpens of recent playoff teams.

I looked at the last 5 years, and found every team that won 87 or more games and found the number of innings pitched by their relief pitchers over the course of the season. I also looked at the last 3 years and last years numbers as well because bullpen use has been trending up. Then I compared the Brewers current pace to those averages:


The Brewers are on pace for 637 innings by their bullpen. This would be 4 standard deviations higher than the five year average, 3.6 higher than the three year average, and 3.3 standard deviations higher than last year's average. Those numbers do not sound sustainable to me. Pace numbers from the first 25 games of the season are always a little questionable, I don't think Didi Gregorious is going to hit 64 home runs for example. A change of just one extra out by the starter every two games would bring their on pace number to below 600, something that seems a lot more realistic(the 2016 Dodgers bullpen threw 590.67 innings).

In addition to looking at the whole bullpen together, I decided to look at individual pitchers as well. Now like I said in the previous paragraph, pace numbers are dubious at this point, but I think they can be illustrative when given that caveat. I looked at the bullpens of the teams who made the World Series for each of the past 5 years, looked at their top 4 relievers, and averages the appearances and innings pitched. Again, I compared them to the Brewers bullpen:



As you can see, Jeffress is on pace for nearly 91 appearances, 4 standard deviations higher than the mean. Hader, it may surprise, is actually on pace for a below average number of appearances. On the second table, though, we see his is on pace for nearly 100 innings pitched, 3.7 standard deviations higher than the mean. One interesting question Craig Counsell seems to be posing is "Does the number of appearances matter, or the number of innings?" If Josh Hader holds up throughout the year, limiting appearances and not innings will have a case study on its side.

Overall, I do not think many definitive conclusions can be made from this analysis other than the bullpen is being used A LOT! We already knew that. A storyline to watch throughout the year is whether or not that will make a difference.