The Pirates completed a trade on Wednesday that sent Joel Hanrahan and Brock Holt to the Red Sox for Mark Melancon, Jerry Sands, Stolmy Pimentel and Ivan De Jesus. The deal increases organizational depth for the Pirates and gives them a solid reliever in Melancon. The deal also effectively makes Jason Grilli the new Pirates closer. Grilli, who was recently re-signed to a very affordable two-year, $6.75 million contract was probably the better bet to close in Pittsburgh even with Hanrahan present.

The subsequent trade of Hanrahan only enhances the value of the contract he signed. Grilli certainly would have been paid more money had he entered free agency as a closer or a reliever seeking closing opportunities. Given his numbers over the last two seasons, it wouldn’t have been crazy to suggest him as a legitimate closer candidate somewhere. Instead, even with strong interest from about half of the league, Grilli stayed in Pittsburgh on a team-friendly contract fit for a 7th or 8th inning reliever.

While Holt, Sands, De Jesus and Pimentel all play a role in this deal, the trade really benefits the Pirates by increasing the cost-effectiveness of their bullpen and allowing them to reallocate their savings to other areas of need. The Pirates essentially replaced their closer with a better and cheaper alternative, brought back another cheap reliever whose peripherals closely match that traded closer and signed a starter with the savings.

I know the ‘Guess That Player’ game can be tiresome, but it has value in separating performance from perception. Consider the statistics of the three aforementioned relievers over the past two seasons:

Reliever A: 128.1 IP, 24.2% K, 9.9% BB, 46.5% GB, 3.28 SIERA

Reliever B: 119.1 IP, 21.3% K, 7.6% BB, 54.0% GB, 2.99 SIERA

Reliever C: 91.1 IP, 33.1% K, 9.6% BB, 36.4% GB, 2.41 SIERA

The first two relievers have very similar peripheral statistics. Reliever A has a slightly higher strikeout rate while Reliever B has him beat in walk rate and groundball rate. Reliever C, meanwhile, has a substantially higher strikeout rate than his peers and basically the same walk rate as Reliever A. His groundball rate is the lowest of the bunch but his SIERA is over a half-run better than Reliever B’s, and almost an entire run better than Reliever A’s.

Reliever A is Joel Hanrahan. Reliever B is Mark Melancon. Reliever C is Jason Grilli.

In looking at those numbers, and going on performance alone, it’s hard to argue with using Grilli as the closer over Hanrahan. After adding in their respective 2013 salaries — Grilli at $2.25 million and Hanrahan at an estimated $7 million — the rationale behind the swap becomes even clearer.

The more interesting comparison, as it relates to this trade, is between Hanrahan and Melancon. Their peripherals are very similar since 2011 but they have prevented runs at divergent rates. Melancon has a 4.07 ERA, 69.7% LOB and .285 BABIP over the past two seasons. Hanrahan has a 2.24 ERA, 83.7% LOB and .258 BABIP.

There may be legitimate non-DIPS reasons for the difference in their run-prevention over the last two seasons but, given the small sample, SIERA serves as a better portent of that sort of thing. Additionally, Melancon falls just short of Super-2 status at two years and 98 days of service, meaning he will likely make around $521,000 again next season.

While Hanrahan may have an advantage at inducing weaker contact or preventing runners from scoring, it probably isn’t worth a $6.5 million difference in salary, especially given their similar peripherals. Melancon could end up with a bloated ERA like he did with the 2012 Red Sox, but if you were going to bet on a reliever bouncing back, the guy with the ~3.0 K/BB ratio and 55% GB rate is a great choice.

After re-signing Grilli the Pirates had approximately $10 million being spent on their setup man and closer this season. By moving Hanrahan for Melancon and taking a flier on Francisco Liriano, they may well be able to replicate the Hanrahan-Grilli tandem’s production at 30% of the cost while improving the rotation.

It’s very possible that Melancon falters and Liriano, as a change of scenery candidate, stinks regardless of the change. However, the Pirates made better use of that $10 million by making this move after re-signing Grilli and bringing in Liriano.