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Astros Ken Giles trade is a bigger deal than you think

Research by Baseball Prospectus writer Russell Carlton shows that the value of a bullpen ace far exceeds the value of a "merely" excellent reliever, and that value extends beyond just the ninth-inning closer.

The Astros benefit from Luke Gregerson's presumed demotion to the eighth inning
The Astros benefit from Luke Gregerson's presumed demotion to the eighth inning
John Rieger-USA TODAY Sports

The second-best part about writing for The Crawfish Boxes, after interacting with our dear, treasured readers ("Suck up!" cried about half of you.) is being a part of our writers' list serv.  We talk about all the things that rarely are worth turning into articles...bad trade scenarios, ridiculing other clubs, etc.

During the hubbub of last week's trade that sent five Astros pitchers to the Phillies in exchange for reliever Ken Giles and a shortstop, I posed the question on our listserv:

"Everybody says relievers are fungible...but is that true for elite relievers?" It seemed an unanswerable question, and aside from idle speculation, nobody provided any answer.

Luckily, Russell Carleton of Baseball Prospectus answered it yesterday.  (LINK, subscription required)

Regrettably, the whole of his excellent article is behind a paywall, but what he finds is startling.  He finds that late-inning (ninth but also eighth) inning ace relievers in save situations are far, far, more valuable than the average run of the mill closer.  No duh, right?  This is what non-saber folks have been telling the rest of us for years.  Well, points to the've earned it.

But for the left-brained of us, now it's more or less quantified.

Carleton defines ace closers as those that regularly convert 90% of their saves instead of 80%.  For 40 save chances, that equates to 36 saves or holds instead of 32 - a fairly minor difference.  He acknowledges the inherent fickleness of small-sample relievers, and that a non-ace closer might have years where he saves 36 or more games in 40 chances, or that an ace closer might have season in which he blows up.  But generally speaking, if you can find a reliever who's more consistently great than others, that's a pretty big deal.

The article was primarily aimed at understanding the over-the-top cost in prospects that the Red Sox paid for ace closer Craig Kimbrel, though he also mention the Astros' acquisition of Giles.  I myself compared Giles to Kimbrel earlier in the week, favorably.  I can't go into too much detail about Carleton's article, because go get your own subscription, but I took two key points away as applied to the Astros.


To put it another way, if I could administer a potion to a closer and have it guarantee that the reliever would protect 90, rather than 80 percent of close leads in the eighth inning, that would be worth 2.2 wins, and that vial of potion should be priced accordingly. The problem is that we know that randomness makes it far from a guarantee that things will work that way. Now, it’s a matter of how confident you are in the potion."..."With the Kimbrel trade, I put the value of moving from an 80 percent closer to a 90 percent closer at 3 wins.

Think about that for a second.  He found that an ace reliever like Kimbrel can be worth approximately 3 WAR more than a reliever who is just 10% less effective in save situations.  That's huge.  Even moreso (and here's the kicker for the Astros), Carleton found that ace eighth-inning relievers are almost exactly as valuable.  Meaning, a 90% hold conversion rate compared to 80% in the eighth inning is equivalent to the difference between a ninth-inning closer converting 90% instead of 80%.  He posits that in the near future (and for some teams, already) eighth-inning relievers are going to start earning contracts that used to be reserved for guys who racked up Saves.

The Astros might have an ace eighth inning guy now by moving Gregerson down in favor of Giles.  Gregerson has a career 2.79 ERA, and converted 87% of save opportunities last season with an 85% career rate.  Pat Neshek has an 85% save opportunity conversion rate (most of those are Holds).  By comparison, Chad Qualls has an 82% conversion rate (81% over the past two seasons), and that difference between him and Gregerson/Neshek is meaningful in terms of WAR, as Carleton shows.

Ken Giles?  In his short career, his conversion rate is 89.2%.

Secondly, in examining reliever contracts, Carleton examines the shelf life of relievers versus starting pitchers and find that relievers drop off in performance at a much younger age than starting pitchers.  Don't tell Neshek, please. This research explains why it may be important that the Astros acquired Giles instead of trading for 30-year-old Andrew Miller.

"But the message is clear. Relievers become a liability to decay more quickly as they get older. So, when signing a free agent, a starter is more likely to hold his value than is a reliever over a few years. We’d expect to see shorter duration contracts for relievers… and that’s exactly what we get."

While Carleton was exploring the phenominon of why relievers don't get 7-year Barry Zito-esque contracts, the likelihood to decay more quickly means that there is a larger chance that Giles, age 25, maintains his present value throughout the duration of his team-controlled years than would an equivalent Free Agent or older trade acquisition.  Look no further than the cherry-picked example of Joe Nathan, who posted Kimbrel-like results from ages 27 to 33, then added almost three-quarters of a run on average to his ERA during subsequent seasons.  At age 40 last season, his career ERA stood at a healthy 2.89, but that is a far cry from the approximately 2.00 that it was prior to turning 34 years old.

This new information is interesting and provides a possible insight into why the Astros thought Giles was worth moving five well-regarded prospects for.  It's not just the acquisition of Giles, a bullpen ace.  But it had to do with his projected sustaining of 2015 levels of performance throughout the next several seasons, and also the collective boost provided by moving their current other bullpen aces (or near-aces, if you want to split hairs) down a rung on the ladder.

The trade makes more sense daily.