Randy "Pink" Choate: Should he stay or should he go?

In the Rays' bullpen exodus, one of the less-mentioned names is that of Randy Choate. Perhaps this is justified, given that Rafael Soriano, Joaquin Benoit, and Grant Balfour (assuming all three are healthy) are clearly better pitchers. That being said, Randy Choate has been excellent the last two years with the Rays as a left-handed specialist.

The chart below details Choate's numbers against lefties in his time with the Rays.

These are excellent numbers. Choate strikes out lefties at a great clip, rarely walks them, and also gives up nearly no home runs to them due to incredible ground ball rates.

Choate's overall numbers don't looks quite so great, however, because he's absolutely horrible against righties. His xFIP was a mind-boggling 5.99 against them and although some of that is probably the result of small sampling size random variation, it's pretty clear that he's meant to be used against righties only in the lowest leverage situations. This impacts his value negatively.

Last season, although Choate made 85 appearances, he only pitched 44.2 innings and acquired .5 wins. Since Choate's at bats against righties are low leverage and assuming his xFIP from the last two years is his true talent level, we can calculate his WAR to be roughly .8 wins if he again pitches 35 innings against lefties.* It's unclear how much money Choate would command on the market but given that he made $700k last year, something in the neighborhood of 2 million is probably what he can expect. Assuming he gets that much, that would put his surplus value at $2 million (with a going rate of $5 million per win). On the surface, if the Rays could re-sign Choate for that much it would be a steal.

That being said, a few other things impact Choate's value.

1. Innings: Although the quality of innings Choate pitches against lefties will be excellent, he will still only be providing a small number of them. The opportunity cost of a roster spot for a player who only pitches 35 innings is something that might need to be considered, although I'm unsure how.
2. Draft Compensation: According to MLBTR, there are 4 teams interested in Choate. It's almost certain that he garners the Rays type B compensation, which according to Victor Wang's seminal work is worth a surplus value $2.6 million. Additionally, this draft is widely considered to be one of the best in a long time and as a result the surplus value might be greater than $2.6 million.
3. The Red Sox Lineup: While the above two factors suggest that Choate's value is less than the above analysis, the Red Sox's new lineup with Adrian Gonzalez and Carl Crawford is tremendously lefty-heavy. It would be nearly impossible to attempt to predict the number of high leverage situations in which Choate would be of use or the amount of impact this would have, but this is probably something worth keeping in mind.

Either way, Randy Choate was not the Rays best reliever last year, but guys like him certainly do have value. While not irreplaceable, it probably isn't a stretch to call him one of the top few lefty specialists in the game. Choate's dominance of the left-handed hitter these last two seasons was excellent, and even though we will get compensation (probably greater than his value to the team) if he signs elsewhere, he will still be missed.