Last June, I took a look at how Buck Showalter managed his bullpen two months into the season using a metric called leverage index. The season was only two months old, so I was hesitant to make any sweeping conclusion. As the Orioles' bullpen this season has so far exploded for an ERA of 5.23, second worst in the league, I think that it's a good time revisit Buck's bullpen management from last season.
Just to refresh your mind, leverage index is a measure of how important a particular situation is in a baseball game depending on the inning, score, outs, and number of players on base, created by Tom Tango. An average (or neutral) LI is 1. High leverage is 1.5 and above, and low leverage is below 1. 10% of all real game situations have a LI greater than 2, while 60% have a LI less than 1.
I included all relievers who made at least 10 appearances from the bullpen for the Orioles. I used the projected RA of the pitchers from Steamer projection. I averaged the projected RA before the 2014 season and the projected RA before the 2015 season as my best estimate of reliever's true talent during the 2014 season.
You can see that the relationship, similar to what I found last June, is modest at best. You want to see a strong negative relationship for your team, signifying that pitcher projected to allow the fewest runs are brought into the game at the most important situations. The correlation between projected RA and the leverage index entering the game for a reliever for the Orioles is only -0.19 (on a scale from -1 to 1, where 1 represents perfect positive relationship, -1 represents perfect negative relationship, and 0 represents no relationship).
The addition of Andrew Miller at the trade deadline boosted that figure significantly, as he was the best arm in the Orioles' bullpen according to Steamer and pitched in most important situations along with Zach Britton.
Britton was projected before last season as a starter, so his projected RA is higher than it would be if he was projected as a reliever. Adjusting his projection would skew the correlation to a more negative number, as he was projected for a RA of 5.26 in 2014 and a RA of 3.63 this season.
The main outlier, similar to my analysis last June, was Evan Meek. Buck had a weird obsession with Meek, bringing him in with the score within one run in 13 of his 23 appearances, with his time in the big leagues separated by stints in the minors.
Other than his handling of Meek's appearances, I would say that Buck did a pretty good job managing the bullpen last season, especially his quick recognition that Britton is the real deal in a relief role. So far this season, he hasn't deviated much from the book. After the success of the bullpen over the last three seasons, I have the confidence in Buck's bullpen management to turn the bullpen performance around this season.