Nunez regressing, no need to demote him

At the beginning of the season, Leo Nunez was on a complete tear. He had walked just five guys and allowed five runs through the first two months of the season (21 2/3 IP). Meanwhile, he had also struck out 23 batters up until that point, an impressive 28.4% mark. Indeed, through June, he had still been pitching pretty well, allowing just 10 runs, walking just eight batters (6.3%) and striking out 32 (25.0%). It looked like the Marlins had made the right decision in terms of which closer to keep. Somehow Nunez had drastically improved his strikeout and walk rates and was not suffering from the same home run problems he had struggled with in 2009. Matt Klaassen of FanGraphs agreed.

However. since then Nunez has struggled. He has thrown 15 2/3 innings and allowed nine more runs, yielding a 4.02 ERA. His season ERA, which had hovered in the low 2’s for much of the year, has climbed up to 3.14. After blowing a save in consecutive nights against the Philadelphia Phillies and St. Louis Cardinals, manager Edwin Rodriguez pointed out that, if Nunez could not improve, he may go with a closer-by-committee approach going forward.

"“We shouldn’t be telling them what to throw. Then again, if it doesn’t work out, I told them, as the manager I have to get it done. I have to look for other options.”"

What I found interesting about this is the reasoning behind Nunez’ recent “problems.” Rodriguez mentions that the problems may arise from Nunez’ overuse of his changeup.

"“If you are confident throwing the changeup, throw the changeup. But you have to be smart,” Rodriguez said. “You don’t even have to throw it for a strike, because they’re sitting on it. Pick your spot and mix your pitches. It could be Leo, it could be anyone."

Apparently this has been a concern since the start of the year. This article from May (which lauds Nunez’ success out of the pen; oh how the times can change during one season when you’re a reliever) says that Nunez sometimes can get in trouble by overusing his changeup. But has this approach really differed from the beginning of the season? Let’s check out the Pitch f/x data available over at Trip Sommers’ awesome Texas Leaguers site.

Knowing that Nunez throws three pitches (a four-seam fastball, a changeup, and a “slider” offering), I grouped pitches that were not classified as either of those three into one of the three categories. I also split up the data into two parts, from the beginning of the season (the first three months, when he was lights out) and the most recent part of the year (through July and August). Here’s what you get:

And in the latter half of the year:

It would seem, just from the data, that he is going less to the slider and more towards his other offerings. While that may be a bit of an issue, I wonder if that is really what is affecting him. In this latter part of the year, he has not allowed a home run and has struck out (27.5%) and walked (5.8%) guys at a similar rate as he did in the so-called “good” part of the year. Yes, he is allowing more hits, with a current BABIP of .467 (!). Some of that may be the added use of the changeup, sure. Some of that could also be just blind variance. Consider that, in these 15 2/3 IP, he has allowed 46 balls in play. The difference between a .467 BABIP and a .300 BABIP (the typical league average) in that amount of BIP is about eight hits.

If there is a difference in the way he has pitched, you would expect to see a significant downturn in multiple areas, including strikeout and walk rates. However, he has not had that downturn. What has happened is about six to eight more hits have squirted through against Nunez than they had in the beginning of the season. He is simply regressing to the mean, and concerns about his slight changes in pitch selection are probably a bit unwarranted. The guy still has an astoundingly low 2.01 FIP, and ZiPS projects a 3.43 ERA and 3.54 FIP going forward. Neither of those would be as good a performance as he had shown in the beginning of the year, but they would perfectly acceptable given what we expected from Nunez before the season began. To get frustrated by two or three bad outings after numerous good ones seems like a bit of overreaction. Given the unreliability of our other bullpen pitchers, I can’t imagine the Marlins giving anyone else much of an opportunity anyway.