Examining manager Mike Matheny's usage of closer Trevor Rosenthal

Full disclosure, Mike Matheny used Trevor Rosenthal correctly in last night's 4-3 victory over the second-place Pittsburgh Pirates. Then again, with eight solid innings from Carlos Martinez and a one run lead with three outs left to record, it was virtually impossible to mess the decision up. As you may recall, Derrick Goold of the St. Louis Post Dispatch recently published a thought-provoking article titled "Matheny: Contracts can't be ignored in setting bullpen roles." Our very own Ben Humphrey already did a fantastic job dissecting Matheny's thoughts, but after a few hours of research (on Fangraphs and Baseball-Reference), I found a uncovered a few things I wanted to discuss as well.

First and foremost, Rosenthal is clearly the Cardinals' best relief pitcher. Sure, it cannot be ignored that the whole bullpen (2.26 ERA in 331.0 IP) has been nothing short of fantastic in 2015. Yet, when you look at career numbers, combined with the makeup of each reliever's repertoire, there is really no doubting that Rosenthal is the best of the bunch. The 25-year-old was rightfully named to his first All-Star team this season and is widely considered one of the top closers in baseball. You probably don't need to see his 2015 stat line as reinforcement, but I will include it anyway:

As I was saying, Goold's article had me thinking about a topic that has crossed my mind in the past but never precipitated into much. If Rosenthal is indeed the team's best relief pitcher, it is not unreasonable to believe that he should be reserved for each game's highest leverage situation, right? Of course, Rosenthal cannot (and should not) pitch in every single game, but when he is available to pitch, he should be pitching in the highest leverage situation. In case you missed it, Scott Boras (Trevor's agent) had comments on Rosenthal's usage during All-Star weekend, via Goold/Post Dispatch.

From a player respect standpoint, I completely understand Matheny's "contracts can't ignored" statement, but given how readily available advanced metrics are these days, there has to be a better way to place value on a player without being detrimental to the club as a whole, right? The short answer is a big maybe. At present, player agents do a terrific job at "selling" their players' statistics to prospective buyers (I will always remember the reportedly extremely in-depth binder Boras used to (unsuccessfully) promote his client Kyle Lohse after the 2013 season), and it is much easier for them to use statistics like the "save" considering that not all teams have "bought into" sabermetrics just yet.

Either way, enter Leverage Index (LI). As explained in the previously-linked Fangraphs primer (and this one further), LI 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." As a frame of reference, an LI of 1.0 is considered average/neutral leverage, an LI less than 0.85 is low leverage, and anything 2.0 or greater is high leverage. For this exercise, I looked specifically at "gmLI," which is a pitcher's average leverage index when he enters the game. Simply put, entering a game with the bases loaded, no outs, and up by one run will have a much higher leverage index than entering a game with a three-run lead and no runners on base.

Well, of Rosenthal's 51 appearances thus far in 2015, he had the highest reliever gmLI in only 22 of them (43%). This means that in 29 (57%) of Rosenthal's games, another reliever (of already-determined lesser quality) pitched in a higher leverage situation. Further, in 12 games, more than one relief pitcher appeared in a higher leverage situation than Rosenthal. Now, this was a slightly different situation when Jordan Walden was healthy and available as the primary set-up man, but he has not pitched since April, and unfortunately, he probably won't be contributing at the big league level any time soon, either.

Realistically, I accept the fact that Matheny (and the rest of MLB managers for that matter) is not going to change the way he uses his closer. He will still wait to bring him into a three-run-lead ninth inning for a save opportunity despite possibly having a higher leverage one-run-lead in the eighth, or even a multiple runners-on-base situation in the seventh (which is usually reserved for Seth Maness).

That being said, Rosenthal has 15 saves this season where he started a clean inning with a three-run lead. If Matheny wants a blueprint for how to use his closer effectively going forward, and I fully understand that the game, to an extent, dictates some of the decision-making process, he did a tremendous job utilizing Rosenthal throughout the month of June, particularly considering it is the only full month in which he did not pitch on back-to-back-to-back days at least once.

Quick notes regarding Rosenthal on back-to-back-to-back days

Surprisingly, Rosenthal's fourseam fastball does not appear to have suffered a velocity decrease in his five appearances at the tail-end of a back-to-back-to-back. In fact, in these games, his fourseamer averaged 98.53 MPH, slightly higher than his 2015 average of 98.38 MPH. His fourseam whiff percentage, too, saw a slight increase to 14.81%, from his 2015 average of 12.23%. Regardless of these interesting tidbits, Rosenthal should not be used three days in a row on a relatively consistent basis (i.e. five times in four and a half months), and no, this is not just because Scott Boras said to be cautious with his client's usage rate, this is common sense.

Bottom line

It would be a refreshing change of pace to see Rosenthal remain in the bullpen during some three-run leads in the future. Either that, or he pitched the inning prior when the lead was only one with the heart of the order due up (read: higher leverage). This is not a change that will happen overnight, but it is something I hope Matheny continues to ponder as his experience as manager grows. Given some of his comments in Goold's piece, it appears to be something he has indeed thought about already, so who knows, maybe he will go against present baseball culture and use his closer differently? No, probably not.

Here is a link to a Google Spreadsheet of my data collection.