At first glance, Santiago Casilla‘s stat line doesn’t look too bad. He currently has a 2-4 record with 21 saves (good for third in the NL) with a 2.84 ERA, but when you pull back things a little further, things don’t look quite as good.
After last nights disaster of a ninth inning, Casilla is now tied for the most meltdowns in all of baseball with 10 on the season. A meltdown is classified as when a player made his team 6% more likely to lose the game (the converse is called a shutdown, you can go here to read more about it). On the season, Casilla now sits at 10 shutdowns and 10 meltdowns, putting him squarely in the below average category.
Looking at his defense independent pitching stats tells much of the same story. His 4.37 FIP ranks 70 of the 94 NL relief pitchers who have thrown at least 20 innings this season, his xFIP an tERA rank 39th, and his SIERA ranks 34th.
Depending on the way that you look at it, he has been an average to below average pitcher. This conclusion is right in line with what he has done for his career. His career FIP- and xFIP- are both 99 (100 is league average, lower numbers are better), meaning that he has been 1 percent better than a league average pitcher.
So the question becomes what should the Giants do their bullpen utilization in light of Casilla not being a bullpen ace?
The tough but sensible answer is nothing. When you take a look at how Bruce Bochy has used his bullpen this season, he has actually used Javier Lopez and Sergio Romo in more high leverage situations, meaning they are utilized in more important game situations as stipulated by inning, score, outs, and number of players on base. Casilla has only the third highest average leverage index on the team.
If the Giants do move someone else into the closer role, it might make the bullpen usage less ideal. Right now, Bochy is using the duo of Lopez and Romo in the highest leverage spots before the ninth inning (and sometimes to clean up the mess if Casilla gets in trouble in the ninth). If instead he uses them to close out the ninth inning, those earlier high leverage spots, which can often be more important than starting off the ninth inning with no one on and no one out, will fall to pitchers who are not as good.
Casilla is arguably the Giants third best pitcher (as long as Lopez is pitching primarily to lefties). Using him as the “closer” frees up Bochy to use his best relievers in higher leverage situations, instead of waiting for the possibility of a save situation that may not come.
Looking at the minors, there isn’t really a guy making a ton of noise to be called up right away, and even if there were, it is unlikely that Bochy would make a rookie the closer for a team with playoff hopes. If you want to argue for using Hensley or Affeldt, you wouldn’t get too much push back from me. Still, moving them into the closer role is only rearranging deck chairs. If a team wants to give away a high quality reliever for peanuts, I’ll gladly take it, but going out and paying through the nose for a name brand closer is a very low return trade considering the relative lack of depth in the farm system.
Though it may not be a glamorous option (especially after I spent all this time explaining why Casilla isn’t an elite relief pitcher), Casilla-as-closer makes the most sense for the Giants.