Long: Do the bullpens that stay together parade together?

From Jeff Long at Baseball Prospectus on April 3, 2015:

How well do you know the relief pitchers on your favorite team? Given the volatility associated with being a reliever, it’s not uncommon for a team to have a bunch of fresh faces sitting out in the bullpen—minor-league free agents cattle-called into spring training, unexciting non-prospects whose stuff played up after moving out of rotations into the bullpen, fallen closers hanging on to careers, or trade throw-ins with enough funk to retire a lefty. Takes all kinds.

Earlier this offseason we tried our hand at critiquing managers for the use, or abuse, of their bullpens; it’s admittedly not exactly a fair exercise for a handful of reasons. The one thing that wasn’t addressed in that analysis was something that managers often have no control over: who the guys in their bullpen are.

There doesn’t seem to be a right method to identify relief talent that will perform well in the following season; at least not a foolproof one. This in turn leads to very different methods. During the San Francisco Giants season preview episode of the Effectively Wild Podcast, Sam and Ben and Grant Brisbee discussed the fact that the Giants had very little turnover in their bullpen. Brisbee acknowledged the absurdity of the Giants’ bullpen continuity, noting for example Jean Machi, who will be going into his third season with the team, is one of the greenest members of the group. The “new” guy.

Inspired by this revelation, I looked into which teams had the longest tenured bullpens last year, and which teams had a whole bullpen full of fresh faces. On average, major-league bullpens are filled with relievers that have been with the team for just 1.2 seasons. Those relievers had spent 3.7 seasons at the major-league level with at least a modest workload. I opted to use a 15 IP cutoff for each season in this study.

Read the full article (subscription required): http://www.baseballprospectus.com/article.php?articleid=25956

Originally published: April 3, 2015. Last Updated: April 3, 2015.