Manufactured Runs: The Year of the Free Agent Relief Pitcher

This appears to be the year of the free-agent relief pitcher.

Even relievers who aren’t free agents this offseason have something to look forward to, as the latest Collective Bargaining Agreement makes it much more difficult for a relief pitcher to cost a team a draft pick in order to sign him. It’d be easy to say that this rule (or rather a variation of it which has already gone into effect following the announcement of the new CBA) is to blame, but the biggest relief pitcher signing of the offseason occurred before the new rule went into effect.

The Phillies nearly had a deal in place to retain closer Ryan Madson for absurd numbers of dollars and years, only to have a change of heart at the last minute and sign Jonathan Papelbon for even more dollars and years. One gets the impression of someone deciding to go on a three-day bender and then after giving the matter a second thought, throwing out all the vodka, and stocking up on ether and Thunderbird. Heath Bell just got $27 million from the Marlins for three years, which for those of you keeping score at home is over half of the Marlins’ entire 2011 payroll. Heck, Jonathan Broxton got four million dollars from the Royals after a physical exam so cursory it apparently couldn’t catch a severe case of clinical freaking death.

But are these contracts good ideas? We of course won’t know for certain for several years, but we do have history to guide us. I took a look at multi-year free agent relief contracts from 2000 through 2011 with an average annual value of at least six million dollars, searching for comparisons with the deals Papelbon and Bell got.  I looked at how well those pitchers did in the three years preceding their contracts, as well as during the contracts:

These free-agent pitchers didn’t pitch as well after their contracts as they did before, either in terms of innings pitched or ERA. They were still decent, but teams expecting their free agent relievers to match their previous accomplishments would be a little disappointed.

Except.

There have been 21 such free agent deals since 2000. Four of those have been signed by one Mariano Rivera. Mariano Rivera is pretty well unprecedented in consistency for a relief pitcher. How well do teams fare signing pricey free-agent relievers who aren’t Mariano Rivera?

Shockingly, our non-Rivera pitchers aren’t as good as Rivera. What we see is, on average, seven fewer innings per season and an increase in ERA of more than 0.30 earned runs. The difference was actually worse than that, though—the league average actually dropped from 4.35 in the “before” periods to 4.20 during these contracts; these pitchers started allowing more runs while the league was actually scoring fewer runs per game. If we translate the “before” performance to the same league average as the “during” performance, we see a drop of about .42 earned runs per game.

Free agent relievers typically don’t hold onto their pre-contract values. General managers who pay a relief pitcher for what he’s done in the past may well find themselves overpaying for what a pitcher is going to do in the future.