The Mets moved Jenrry Mejia to the bullpen in back in May and made him the team's closer shortly thereafter. From the time he was moved out of the rotation through the end of the season, he had a 2.72 ERA and went 28-for-31 in save opportunities. On the surface, it appears that Mejia was a solid closer, but you’ll find some major red flags when you take a closer look.
As a relief pitcher, Mejia had a 1.42 WHIP, which ranks 172nd among the 209 relief pitchers who threw at least 30 innings this season. Opponents hit .263/.333/.368 against him in the role, and gave up 59 hits and walked 20 opposing hitters in 56.1 innings. He converted as many saves as he did partially because he induced a high number of ground ball double plays.
Bobby Parnell, who is recovering from Tommy John surgery, should reclaim his role as closer in 2015. He will continue his rehab in spring training and could be ready for start of the the season if he is fully recovered twelve months after the surgery. There's no guarantee of that, but some pitchers have returned that quickly.
Parnell was named the closer before the 2013 season and had the best year of his career. He posted a 2.16 ERA with a 1.00 WHIP and 22 saves that season. He also held opponents to a slash line of .211/.260/.294. His development as a closer really took a turn for the better when he unleashed his newest weapon, the knuckle curve. This was a very effective pitch that kept hitters off balance and forced them to look for something other than his high-90s fastball.
In order to analyze the effectiveness of Parnell and Mejia in late game situations, let’s take a look at the difference between them in a statistical category that is important when evaluating closers: leverage, which measures the importance of the situation when a reliever enters the game.
Parnell was much better in high-leverage situations, which is exactly what a team would want from its closer. Obviously it’s impossible to predict whether Parnell will be able to replicate the success he had in 2013 after having Tommy John surgery, but he deserves the chance to prove himself. Mejia still has the chance to improve as a relief pitcher, but he has not done enough to dethrone Parnell as the closer.