Bobby Parnell has struggled in rehab outings

Mets reliever Bobby Parnell has officially rejoined the team today, but his struggles during the rehab assignment are cause for concern. Making his return from Tommy John Surgery that took place last April, Parnell has put up awful numbers in the minors this season.

Over the course of 15 appearances with Single-A St. Lucie and Double-A Binghamton, he has an 11.57 ERA and 2.45 WHIP while opposing batters have hit .373 against him. He has allowed at least one run ten times in those fifteen appearances—and multiple runs five times. He has also failed to convert any of his three save opportunities.

These numbers might just be a byproduct of rust, as Parnell has pitched in just one MLB game since the conclusion of the 2013 season. But they might also be indicative of a significantly lower velocity. In the past, Parnell relied on a mid-to-high-90s fastball to get batters out. But according to ESPN, Parnell’s once-dominant fastball has only topped out at 92 miles per hour this season. This represents a steep decline in velocity from a pitcher whose fastball once topped out at 103 miles per hour.

Unlike past years where relief pitching was the team’s Achilles heel, the Mets’ bullpen has been good this season, sporting the second best ERA in the National League and the third best in all of baseball. If he can return to his previous form, Parnell would obviously provide manager Terry Collins with another solid bullpen arm.

In his last full season in 2013, Parnell recorded a 2.16 ERA in 49 appearances. He served as the team’s primary closer that year and earned 22 saves. But if he struggles again like has in the minors this season, the Mets may have no choice but to get rid of him. With the team just a half game out of first place, there is very little room for error.

The Mets must now hope that Parnell’s poor rehab showing was due to rust and not decline, and that he will be able to put up his pre-surgery numbers again. He is statistically one of the best relievers the team has had in recent years and his past experience as a closer would ideally make him a valuable addition to an already flourishing bullpen.