Will Koji Uehara close for Red Sox next season?

The Red Sox have made clear that they’re very committed to Koji Uehara, signing him to a 2 year/$18M contract this week, not even letting him reach free agency. Considering Uehara’s collapse down the stretch in 2014 and the emergence of Edward Mujica, however, it’s worth wondering whether the Red Sox plan to use Uehara as their closer next season.

Boston originally signed Uehara to a 1 year/$4M deal with a vesting option for 2014 during their spending spree in the 2012-2013 offseason. Uehara served as a setup man through the early portion of the year but, due to injuries to Joel Hanrahan and Andrew Bailey, became closer. After becoming the closer, Uehara’s year turned from an excellent season to arguably the best season that a relief pitcher has ever had.

In 73 appearances in 2013, Uehara posted a remarkable 1.09 ERA backed up by a similarly stingy 1.61 FIP, 12.2 K/9, and 1.1 BB/9, a season that included a streak of 37 consecutive batters retired by Uehara. He continued his dominance into the postseason as he won ALCS MVP en route to a World Series title.

Needless to say, Uehara was slated to start the 2014 season as closer and he was excellent once again for most of last season. In the first half of the year, Uehara posted a phenomenal 1.65 ERA and a 9.50 K/BB in 42 appearances, looking every bit the stud he had been in his historically-good 2013.

The second half of the season was a completely different story, though.

Uehara struggled to the tune of a 4.35 ERA and, while his excellent peripherals continued, he just looked… hittable. Uehara blew three saves in the second half and allowed 10 earned runs in 5.1 innings pitched over a six-game stretch, watching his ERA more than double from 1.27 to 2.64.

There are a number of possible causes for Uehara’s implosion: heavy workload– the 39-year old Uehara had thrown 88 innings (including the postseason) the previous season and 66.2 to that point in 2014, his age finally catching up to him, or just a random and devastating patch of bad luck. Obviously the Red Sox are not concerned with that six-game stretch, though, as they had no problem signing Uehara to a fairly substantial contract considering his age and the questions surrounding his future performance.

With that large contract commitment, though, can the Red Sox count on Uehara as their closer? It appears that the most realistic cause for Uehara’s collapse is heavy workload on his aging arm and, if that is the case, then they may not be able to utilize him as a full-time closer.

Of course, provided that he returns– or at least approaches– his performance in the first half of 2014, the Red Sox would be foolish not to use him to close games. Even at 39 years old, Uehara has the potential to be as dominant as any closer in the game. However, the Red Sox must be very careful not to overuse Uehara and fulfilling that hope could represent a major part of their offseason plan.

If the Red Sox are able to sign an elite late-inning arm, they should be able to effectively limit Uehara’s appearances. Between Uehara, Edward Mujica (who turned it on in the second half and could be a candidate to close in a pinch), Junichi Tazawa, and a potential acquisition, the Red Sox should be able to use a more economical late-inning approach. While Uehara should receive the majority of the ninth-inning appearances, the Red Sox must make sure not to overuse their veteran closer. Otherwise, it’s entirely possible that this contract could be major mistake for the Red Sox.