A couple articles out there about relief pitchers. Buster Olney wrote today about the Braves' important arbitration case with Craig Kimbrel:

But the gap between what the Braves have offered Kimbrel -- $6.55 million -- and what Kimbrel wants in arbitration -- $9 million -- is enormous, and there’s more at stake for Atlanta in this hearing than the $2.45 million that separates the sides. If the Braves win the case, they will give themselves a legitimate chance to keep Kimbrel for 2015. If they lose, however, then Kimbrel may be priced off the Atlanta roster sooner than anybody expects. Because arbitration cases are like building blocks, with one decision stacked upon the next. If Kimbrel wins his case and makes $9 million in 2014, then he will be well-positioned to ask for something in the range of $14 million-$15 million next year -- or, in other words, he could become the highest-paid reliever in baseball in his second year of arbitration eligibility.

The Braves' payroll has remained about the same for the past decade, due in part to an ill-signed local TV contract. Maybe it will increase with the move to the new ballpark in Cobb County, but that's years away. Complicating matters is the Braves will have other young players eventually hitting their arbitration years -- Freddie Freeman, Jason Heyward and Mike Minor (who signed for $3.8 million) this year, Andrelton Simmons and Julio Teheran in 2016.

As dominant as Kimbrel has been, that makes him a possible trade candidate, especially if he wins his arbitration cases. But as Buster points out, "Kimbrel's actual value in the trade market almost certainly will be substantially less than what fans perceive that it should be, because there will be only a small handful of teams willing to pay a closer $15 million or more."

In contrast to the Braves' situation with Kimbrel we've seen the A's and Rays -- the small-market, penny-pinching, study-every-facet-of-the-game-to-find-any-edge-possible A's and Rays -- spend money on their bullpens this offseason. The A's lost closer Grant Balfour, who made $4.5 million in 2013, but traded for Orioles closer Jim Johnson ($10 million salary) and Padres reliever Luke Gregerson ($5.065 million) and signed free agent Eric O'Flaherty ($1.5 million). The Rays lost closer Fernando Rodney, but rather than promote from within, they first acquired Heath Bell (they'll pay $5.5 million of his $10 million salary) and then signed Balfour to a two-year, $12 million deal after the Orioles backed out of their initial agreement with him.

So what gives? Traditionally, sabermetricians have argued that bad teams or small-market teams shouldn't spend money on relief pitchers; if there's one area to scrimp on, make it the bullpen, in part because relievers are notoriously unpredictable from year to year, in part because starting pitchers are more valuable, but also because you can build a cheap but effective pen with young relievers (think of the A's with Ryan Cook and Sean Doolittle).

Russell Carleton of Baseball Prospectus tackled this subject earlier in the week in an article titled, "Why Are Smart Teams Spending Money on Relievers?" The article is behind the BP subscription service, but Russell writes,

I’d argue that WAR(P), as we have defined it, doesn't do a very good job of describing relievers. The disconnect can be summed up by looking first at this chart and then at this one. In case you don't want to click through, the first chart is a listing of the top WARs of 2013, while the second is the top win probability added (WPA) scores of 2013. The WAR chart Top 30 doesn't contain any relievers at all. The WPA chart alternates between elite starters and back-end relievers, mostly closers. There's a lesson in here, if you're careful to look for it.

Basically, WPA will give a closer like Greg Holland a lot of value because he's almost always pitching in high-leverage situations. It's not a perfect metric, but it explains why closers or setup men can be considered more valuable than what WAR describes them to be. As Russell writes, "Holland had a good year, no doubt, but more importantly, he illustrates a point. Because teams have a lot more control over what relievers are placed into what situations, having a good reliever (or a reliever having a fluky good season) for those high-leverage situations can have a big impact on a team's chances of winning games."

I often write that closers are overrated. That's different from saying they aren't important. What I mean when I say that is that the halo effect we tend to put around closers is wrong. Look at the Yankees. Right now, everybody is worried about replacing Mariano Rivera. But David Robertson will be fine in the role because Robertson is an outstanding relief pitcher. The more difficult task for the Yankees will be replacing Robertson's innings (which they've yet to do) than Rivera's innings. Yes, you can find examples of good setup guys who maybe couldn't handle the ninth inning, but nearly all good setup relievers will be good closers if given the opportunity.

Also, relievers are easier to find. Many relievers are failed starters. Put them in the pen and suddenly their fastballs ramp up a couple of mph and they can focus on two pitches instead of three or four. Look at former Rays starter Wade Davis. He wasn't very good in the rotation, but was outstanding when moved to the bullpen in 2012. Traded to the Royals, they tried him again as a starter and he was terrible. Or his Kansas City teammate Luke Hochevar, who never made it as a starter, with a 5.45 ERA over five seasons. Moved to the bullpen in 2013, he posted a 1.92 ERA with outstanding peripherals.

That's what I mean about being overrated. And calling relievers overrated is why Kimbrel's trade value is minimal. Ultimately, teams feel that they can always find a closer, so why give up value and pay Kimbrel a big salary?

You still want a good bullpen, of course. In terms of WPA, the only playoff team not in the top half of the league in 2013 was the Rays, who ranked 18th. Even the much-maligned Tigers pen ranked 15th.

It's also worth mentioning that the deeper your pen is, the less work you'll require from your starting pitchers. In Oakland's case, they don't yet have any proven 200-inning workhorses in the rotation (although Jarrod Parker may get there this year), so a deep bullpen will allow manager Bob Melvin to have quicker hooks with his starters.

The A's and Rays don't have a lot of money to spend on a new cleanup hitter or No. 3 starter. But they can afford relief pitchers and that's why general manager Billy Beane traded for Johnson and the Rays signed Balfour.