Evaluating The Twins Bullpen: Part 1

There are two main features of the Twins’ bullpen so far in 2015: it’s bad, and it’s old. Let’s start off with the bad. Here is a rundown of how the pen is performing in a number of key categories:

ERA: 4.01 (21st in MLB)

FIP: 4.19 (25th in MLB)

WAR: .4 (23)

These numbers make it pretty clear that the Twins bullpen is in the bottom third of the league. Why has the bullpen performed so poorly? The answer is a combination of a lack of strikeouts and an inability to generate ground balls, which is leading to a high number of home runs. Look for yourself:

K%: 15.6% (30)

BB%: 6.6% (2)

K/BB: 2.34 (22)

GB/FB: 1.09 (27)

HR/9: 1.0 (22)

Poor performance in these categories—the three “true outcomes”—makes it pretty difficult to find sustainable success. Therefore, unless the Twins make a dramatic improvement in these peripheral numbers, don’t expect their overall performance to improve.

Now, on to the age issue. In case you weren’t aware, the Twins have a pretty old bullpen. The average age of the members of the Twins bullpen, weighted for innings pitched¹, is 30.0 years old. I don’t have numbers for the average age of other bullpens in MLB, but I would be willing to bet that the Twins have one of the oldest bullpens in all of baseball.

To summarize: in case you hadn’t noticed, the Twins bullpen consists of (1) old pitchers who (2) don’t strikeout many batters and (3) fail to generate many ground balls. The result is one of the worst bullpens in all of baseball. Yes, we have a stud closer, but outside of Perkins, it wouldn’t surprise me if the Twins have the worst bullpen in all of baseball.

So why do we care? Obviously, a good bullpen is an important part of a team’s success. But beyond that, having an old bullpen means it’s less likely that our relief pitchers will make significant improvements in their individual performances over the course of the rest of the season. Furthermore, if the Twins do fall out of contention, it would be beneficial, long-term, for the club to give some younger players some experience at the big league level.

1: The sum, for all relievers, of each pitcher's age multiplied by the percentage of the bullpen's IP that they have accounted for.