The Miami Marlins had a series of fantastic pitching performances from their supporting starters once Jose Fernandez went down to a season-ending elbow injury. Most of those pitchers had unequivocally good seasons given their expectations to begin the year. Henderson Alvarez returned to form and put up 180 innings with an ERA less than 3.00. Tom Koehler surprised everyone with an improved strikeout rate. Jarred Cosart went from broken former prospect to competent groundballer for a while in Miami.
But one player had a season that was both good and bad for the Fish. Nathan Eovaldi started off the year hot, but his strikeouts quickly cooled off and by midseason had returned essentially to his old levels. This accompanied a mild decrease in fastball velocity which was fixed, but the problems with Eovaldi persisted. His ERA at the end of the year was a disappointing 4.38, and that left him essentially value-less according to Baseball-Reference Wins Above Replacement (WAR). According to their version of the wins metric, which is calculated by taking actual runs allowed and subtracting out the team's defensive component prorated for the number of batted balls allowed, Eovaldi was a replacement-level starter this season.
But then again, there was the other side of the coin. Eovaldi posted an even strikeout rate compared to last year, which was clearly a success for Miami. At the same time, he dropped his walk rate from 8.9 percent to 5.0 percent. He also allowed a similar number of home runs this year as compared to last season. In short, the things that Eovaldi had the most control over, he did well. His fielding-independent statistics were excellent, better than in his strong 2013 season.
Eovaldi allowed more hits on balls in play in 2014, with a BABIP of .323 versus a .286 mark in 2013. Most pitchers exhibit very little year-to-year correlation in those types of numbers, indicating that BABIP has less to do with skill relative to other Major League players. In other words, all Major Leaguers have the ability to suppress hits on balls in play, and the variance of that skill in the bigs is very small. The range of the lowest and highest BABIPs from 2012 to 2014 is between .259 (Jered Weaver) and .326 (Ivan Nova). While it is perfectly possible that Eovaldi, who has the tenth highest BABIP since 2012 on that list, could remain up in the upper limits, it seems far more likely that he will regress to the mean for next season since he is closer to an extreme right now than the average.
This is compounded by the fact that Eovaldi pitched well in other aspects of his game. It does not seem likely that he would collapse in one aspect when his underlying performance still appears to be intact. It is much more likely that this season's failure with men on base and with BABIP is similar to last season's relative success in that department: a blip in the radar heading towards to league average.
Nathan Eovaldi posted a 3.37 FIP, and by FanGraphs' interpretation of WAR, that was worth three wins this season. That's a better mark in 2014 than guys like Sonny Gray, Julio Teheran, and Zack Wheeler put up this past year. The discrepancy likely means that Eovaldi's value last season was somewhere in between useless and above average, which makes for a negative compared to his expectations. But the fact that things should be looking up for him next season is at least a good sign.