2016 Stats: 42.1 IP, 3.40 ERA, 1.28 WHIP, .265 BAA, 8.08 K/9, 0.3 WAR
Mike Dunn has been a staple as the left-handed pitcher in the Marlins bullpen since 2011 and has always been a workhorse. Since coming over from the Braves in the Dan Uggla trade in the winter of 2010, Dunn has made 60 or more appearances in every season with the Marlins before this year.
In 2016, Dunn made only 51 appearances on only 42 1⁄3 innings pitched, and his overall numbers changed in the wrong direction as compared to the rest of his career. His 1.28 WHIP and 3.40 ERA were both right around his career average, but the more advanced stats showed more struggles for Dunn. The lefty has never been much of a lefty-killer in his career, and has mostly had fairly even numbers against left and right-handed hitters, but he became a reverse splits pitcher in 2016. Lefties hit a concerning .279 off of Dunn this season and righties hit .256.
The trends of how Dunn gets hitters out changed in 2016, and so did his effectiveness. He has allowed opposing lefties to hit only .224 in his career with a wOBA of .287, but both of those numbers jumped drastically this season. Although he was better against righties than lefties this season, Dunn’s career batting average allowed to righties is .235, which is much lower than the average he allowed in 2016.
The other thing that hurt Dunn in 2016 was his drop in strikeouts. The 31-year-old had averaged over 9.50 strikeouts per nine every year of his career coming into 2016, but this season that number dropped to 8.08. The strikeout drop showed up even more against lefties, and can be contributed to the significant drop-off of the effectiveness of his slider. Dunn’s slider was hit more in 2016 than it had ever been, and in previous years it had been his strikeout pitch, but that was not the case this season.
The one positive for Dunn this season was his decrease in walks. He allowed only 2.34 walks per nine innings, which by far was the best of his career. Keeping the walks down did help the WHIP and the ERA, but Dunn was still hit around a lot more than usual, so it all basically evened out.
Dunn is now a free agent, and is just another pitcher that the Marlins have to worry about possibly re-signing. Miami will want to have a good lefty in the bullpen that can get lefties out at a high rate, and Dunn did not show that he could do that in 2016. The mid-season addition of left-hander Hunter Cervenka and his better numbers against lefties will also hurt Dunn’s chances of signing another contract with Miami. If the Marlins can get him back at a low price, they could re-sign Mike Dunn for 2017, but that does not seem likely after his 2016 struggles.