Is Brad Mills Using His Bullpen Effectively?

Any time a team plays as badly as the Astros have this season, people are going to question its manager. Most of the criticism Brad Mills has received revolves around how he uses his bullpen. Statistically, Mills’ bullpen is the worst in the league. The Astros are tied with the Nationals for the lead in blown saves with 17 and only the Minnesota Twins’ pen gives up more runs. It’s safe to say the pen has been bad. But is Mills to blame? Has he used his various pen pieces as effectively as possible?

Recently, it seems that no matter which reliever Mills brings in, the lead (or tie…or close score) vanishes immediately. I decided to look at righty/lefty splits and leverage index to see if Mills is using his pen effectively. Basically, by looking at the righty/lefty splits, we can make sure that Mills isn’t making a similar mistake to the one the  Oakland A’s are apparently making with Brian Fuentes this year. And looking at leverage indexes can help us determine if Mills is using his best relievers in the most crucial situations. Leverage index is a stat created by Tom Tango that measures how important a particular situation is in a baseball game depending on the inning, score, outs, and number of players on base. High leverage situations are easy to spot when they are happening. This stat gives a number to these situations and allows us to see how relievers are being used.

Looking at the Astros lefty/righty splits reveals that they have used four pitchers this season who have been significantly better against either right handed or left handed batters. Brandon Lyon is the first pitcher I noticed with significant splits. Before his injury, or perhaps in spite of it,  Lyon actually pitched pretty well against right handed batters. However, he was completely ineffective against lefties. I don’t necessarily blame Mills for using Lyon against lefties early on. If you are going to use him as a closer, it has to be because you think he can get out both types of batters. He has pitched well enough against lefties in the past to allow him to be a decent closer. Obviously, I think Mills hoped that Lyon could regain his form from last year and hold down the closer’s role. Jeff Fulchino is another pitcher who has been used equally against righties and lefties. While his ERA has only been slightly worse against lefties than it is against righties, his FIP splits reveal his inability to keep the ball in the yard against lefties. This suggests to me that he might be better used exclusively against righties. Enerio Del Rosario also has a better FIP against righties than lefties. While his ERA is similar against  righties and lefties, the fact that he walks LHB at a ridiculous rate and that they are hitting .321 off him suggest that he should not be used frequently against them. The biggest area where the Astros could improve the pen concerning these splits is swapping the roles of Fernando Abad and Sergio Escalona. Escalona, in a somewhat small sample size, has been good against lefties and righties. Abad, on the other hand, has been dominant against lefties, but pretty awful against righties. Mills has been using Escalona as a left-handed specialist while using Abad against more righties than lefties. It will be interesting to see if Mills begins to change the way he uses Escalona and Abad as the season progresses.

Left/Right Splits

Leverage Index

When we look at leverage index, we see that the mistakes Mills has made are sticking with Lyon for as long as he did and trusting Abad against righties and in high leverage situations. Again, it looks like Abad and Escalona should probably swap roles. Escalona’s sample size is small. However, early on, it looks like he might be a better choice than Abad in higher leverage situations because of his ability to get out righties and lefties. That being said, if Mills needs a key out against a lefty, I see no problem in bringing in Fernando Abad. And speaking of Fernandos, Fernando Rodriguez should definitely be recalled from Oklahoma City. When he gets here, he should be used in higher leverage situations.

Looking at the left/right splits and leverage index, the big things that jump out are the misuse of Fernando Abad, and the Brandon Lyon situation. Without getting into too much minutiae, and just taking a broad look at Mills’ tendencies, it looks like Mills has made a few mistakes in the way he uses some of his guys and these mistakes have been compounded by the fact that he really hasn’t had a lot to work with to begin with.