But a deep stable of starters can be even more valuable in the offseason, as we've seen this winter. Many of the Hot Stove season's major swaps have involved one club with excess starting pitching, a commodity that's growing more valuable with the exorbitant cost of free agents.
The D-backs, with a strong rotation and a plethora of top pitching prospects, shipped the highly regarded Trevor Bauer to the Indians. The Rays finally tapped into their surplus of starters, sending James Shields and Wade Davis to the Royals. The Braves bolstered their bullpen by parting with Tommy Hanson.
There's a delicate balance to be found, of course. Trade some of your depth, and you can incrementally upgrade another part of your roster or strengthen your farm system. Trade too much of your depth, and all of a sudden one injury can drastically alter your rotation.
"It's an interesting situation to be in," Tampa Bay manager Joe Maddon said. "I know you lose that 1-0 game or that 2-1 game, start bemoaning the fact you've got it figured out. But you've got to figure it out somehow. If nightly we have to do that, I understand that. But to me, to be as pitching rich as you possibly can is a good way to go."
That proved to be true for the 2012 A's. They sent ace Gio Gonzalez to the Nationals last offseason for a package of prospects, and Oakland still featured a glut of pitching that ended up pushing it toward a surprising American League West title. Meanwhile, Washington wound up with a rotation talented and deep enough to put together the best record in baseball despite shutting down its best pitcher in mid-September.
The trend continued this year, most recently with the D-backs shipping Bauer to the Indians in a three-way trade that landed Arizona its long-term solution at shortstop in Didi Gregorius. The D-backs still have seven Major League-caliber starters and a wealth of young pitching, including half of their Top 20 Prospects as ranked by MLB.com.
"We were fortunate that we have a lot of pitching depth," Arizona general manager Kevin Towers said. "There's no doubt in my mind that [Bauer is] going to be a successful big league pitcher. We're just fortunate that we have depth and were able to acquire a premier shortstop."
The Rays have been the poster team for the supposed too-much-pitching quandary over the past few seasons. They spent most of 2012 with as many as eight Major League-ready starters. Davis was pushed to the bullpen. Chris Archer spent most of his time in the Minors. Alex Cobb found an opportunity only after Jeff Niemann was injured.
Then again, Tampa Bay's strength has always been its pitching. The Rays' strong rotation has led them to sustained success in the AL East since 2008, but their depth has also led to several of their most important roster moves.
Tampa Bay picked up outfielder Matt Joyce, an All-Star in 2011, by dealing Edwin Jackson in December 2008. The Rays added infielder Sean Rodriguez and pitcher Alex Torres by parting with Scott Kazmir in August 2009. They acquired Archer, outfielders Sam Fuld and Brandon Guyer, catcher Robinson Chirinos and shortstop Hak-Ju Lee by pulling the trigger on a trade that sent Matt Garza to the Cubs in January 2011.
Tampa Bay's front office has reason to believe that pitching will continue to be the club's strength for years to come, given the prospects in the organization. Meanwhile, the exact opposite was true for Kansas City, rich with young hitters and position player prospects but desperately searching for starting pitchers.
So Andrew Friedman, the Rays' opportunistic executive vice president of baseball operations, saw a fit -- one that would satisfy the Royals' need for starters and keep Tampa Bay's cost-efficient system running -- if he was willing to pay the price.
The Rays somewhat surprisingly dealt away two of their best arms, sending Shields and Davis to the Royals for a group of prospects highlighted by outfielder Wil Myers, who projects to be the kind of young hitter Tampa Bay hasn't developed since Evan Longoria.
"It's never an easy thing to do," Friedman admitted. "I don't think we set out to trade two. But as we started going through things and talking about different scenarios, it lined up in such a way that it made sense for both teams. ... We had a real surplus on the pitching side and not as much on the offensive side."
The Rays certainly aren't the only team using their stable of young arms to improve elsewhere. Look at what the Braves did before the Winter Meetings, shipping out Hanson to the Angels and beefing up their already formidable bullpen with a live arm in Jordan Walden. While Hanson's once-bright future in a Braves uniform is over, the move nonetheless rewarded Atlanta for its success in producing big league starters.
"We felt like we would be able to cover our starting needs with our young [pitchers]," Braves GM Frank Wren said after the trade. "The area we wanted to reinforce was to put another power arm in our bullpen."
As useful as rotation depth can be in patching up other parts of the roster, the few clubs fortunate enough to find themselves sitting on a surplus of starters would argue that it's the same as any other form of currency, if not even more valuable. You can "spend" it all you want, sure. But Friedman often expresses his fear of the idea that his small-market team might one day run out of depth, forced to fill its pitching needs on an increasingly expensive open market it can't afford.
That's why clubs must be cautious when the time comes to pull the trigger and trim down the kind of depth other clubs salivate over. Because there is a reason we so often hear that old adage about never having too much pitching.
"If you're really blown away by somebody, yeah, it makes all the sense in the world [to trade extra pitching]," Maddon said. "But if you're not, I'd rather keep that arm."