When Mo went down for the season, followed by a DL stint for David Robertson, Rafael Soriano became Girardi’s choice to inherit the closer’s role. Things have worked out peachily — Soriano has 17 saves and a Rivera-esque 1.84 ERA. Yet, when we dig a little deeper, we see some good news and bad news.

The bad news is that the stoic shirt untucker is surely not a true 1.84 ERA pitcher and we shouldn’t expect him to be within shouting distance of that range going forward.

Soriano’s 7.98 K/9 is solid enough, but there are 100 relief pitchers (min 20 innings) with better strikeout rates. His walk rate is high at 3.68 BB/9 (113th among RPs), and he’s giving up a TON of line drives (27%, 11th-worst among RPs). While that last number will surely regress, his track record says that they’ll mostly turn into flyballs — not what you’re looking for in Yankee Stadium.

Add it all up and you’ve got a 4.06 xFIP pitcher, putting his skill set behind 116 other relief pitchers.

In his career, Soriano has managed to outperform his xFIP by .9 runs, which is not crazy for a reliever. But even if you generously credit that whole difference as pure skill, Soriano would be a 3.17 ERA pitcher. That would still put him behind 87 other relief pitchers.

Soriano is simply not the dominant pitcher you’d think he was from watching his run of success and looking at his surface stats. But there is a bright side to this analysis…

Even if Soriano does regress to being a 3-something ERA guy the rest of the way, this is not likely to have a huge impact on the Yankees playoff hopes.

Moreover, Soriano’s ERA and save totals make for a glossy, attractive asset to other teams, and with 2013 being the last on his deal, the Boras-led client may opt out at the close of this season to pursue a multi-year contract. This would save the Yankees $14 million next year.

This does not erase the patent mistake the organization made in signing him, considering they would have paid him $21 million for what will likely be somewhere around 2 wins (1.1 WAR since 2011). However, with an ownership group mandating the club be under the luxury tax threshold, not paying a replaceable reliever $14 million would give the team some room for flexibility and creativity.