Rafael Soriano has been great since taking over as the Yankee closer. He has converted 12 out of 13 save opportunities and only given up three runs in the process. But, now that David Robertson is once again healthy should he be reinstated as the Yankee closer?

When Mariano Rivera was knocked out for the season with a torn ACL Yankee manager Joe Girardi named Robertson the team’s closer. In his second appearance as closer, Robertson blew a save opportunity when he was knocked around for 4 earned runs against the Tampa Bay Rays; people often forget that before he blew that save he had not given up a run since August 29th 2011. Two days later, Robertson strained his left oblique and landed on the 15-day DL. In his absence Soriano took over the role.

Since returning from the DL, Robertson has moved back into his old roll as the 8th-inning guy, but the question remains, is he a better option to close than Soriano? To decide who is better suited to close we must define what makes an effective reliever.

First off, let’s quickly explore and recognize that there is a difference in what makes effective relief pitchers vs. starting pitchers. A starting pitcher can be effective in a multitude of ways. A ground-baller who pitches to contact can be just as effective as a fly ball strikeout pitcher; however, a relief pitcher is a much more specialized position due to the situations they are brought into.

Depending on the situation a ground ball or fly ball could cost your team the game. That being said it is vital for a reliever to be able to get outs without putting the ball in play and to get swings and misses. You also cannot give up walks as a reliever because it is the second easiest way to help get your opponent back into the game. All of a sudden a three-run lead looks a lot smaller when you walk the first two hitters and put the tying run at the plate. Lastly, a relief pitcher must keep the ball in the ballpark – the easiest way to allow your opponent back in the game. I know the last two traits seem obvious because it is important for all pitchers to limit BB and HR but I believe it’s importance is magnified as a reliever.

In my mind, an ideal reliever is one that can get strikeouts while missing a lot of bats (keeping runners off base and limiting home runs is assumed). With the above definition in mind Robertson, statistically speaking, should be the Yankee closer. In 2012 he has a better K% (39.1% vs. 19.8%), WHIP (1.24 vs. 1.42), Swing and Miss percentage (25.6% vs. 22.7%) and FIP (1.81 vs. 2.50) than Soriano. Robertson also, over his career, has a slightly lower HR/9 (0.58 vs. 0.84); Soriano has not given up a HR in 2012 but that’s not sustainable. Soriano does have the advantage of a better BB%, ERA, and the experience of being a proven closer.

One of the biggest knocks on Robertson is that he walks too many batters and Soriano has done a good job of limiting walks throughout his career (BB% of 9.0). However, I see Soriano’s 1.78 ERA vs. Robertson’s 2.93 ERA having more to do with luck. Soriano has the lower BABIP (.329 vs. .375) but has a higher LD% (24.4 vs. 18.2); this tells me that batters have been getting better swings against Soriano than Robertson but a lot more balls put in play against Robertson have dropped in for hits.

Soriano’s greatest advantage over Robertson is his experience as a closer in the AL East. Pitching in the AL East is not like pitching in the NL West and the fact that Soriano has proven he can do so (check his 2010 stats with the Tampa Bay Rays) makes a great case for him to close. As you will come to notice from my articles, I am a big believer in using statistics to advance and better explain the game of baseball. That said, the game is not played on a spreadsheet by numbers, it’s played on a diamond by people. One of the best examples of this is a pitcher who has proven he can pitch in the pressure cooker that is the 9th inning. Not every reliever has that 9th inning fire in him and many have questioned whether Robertson possesses that fire.

According to Baseball-Reference.com’s Leverage Index, Robertson actually performs better in high-leverage situations (.196 BA/.559 OPS) than low-leverage situations (.240 BA/.694 OPS). The Leverage Index attempts to quantify how players perform in pivotal moments of the games where dramatic swings in win probability are possible (runner on second late in a tie games vs. late innings of a 12-run blowout). Also, Robertson has a 2.05 ERA in save situations vs. a 3.40 ERA in non-save situations.

I believe, given a real chance Robertson will be lights-out as a closer and likely better than Soriano. However, I think Robertson is better suited to be the set-up man for the 2012 Yankees. The Yankees have the rare luxury of having a proven AL East closer in Soriano which means they can use Robertson in high-leverage situations, runners on base and less than two outs, where he can better utilize his phenomenal strikeout rate. There is no one else on the Yankees’ roster I would trust more to get a big strikeout than Robertson; regardless of the situation. While I conclude that Robertson is the better reliever, he can better help his team this year, as the set-up man rather than the closer. Although, if Soriano begins to struggle don’t be surprised if the Yankees give Robertson a chance to retake the closer role.

Thanks to Baseball-Reference and FanGraphs for the statistics.