Should pitchers work in pairs?

When deciding whether or not to attend a baseball game, one of the first thing most fans do is check the starting pitching match-up. What if a team did away with traditional starting pitchers, opting instead to go with a tandem of pitchers in each game? Yesterday, Russell Carleton at Baseball Prospectus asked that very question:

Here's a question: Suppose that baseball strategy were being re-invented from the ground up, with full knowledge of how the game works. Would the starting rotation be re-introduced in its current form? How much does the existence of the "We have five starters who pitch six or seven innings each and then relievers who take care of the rest" paradigm owe to good logical sense, and how much to the fact that it's always been this way?

The article proposes a new system, in which teams use 6 pitchers, split into three pairs to fill the innings normally filled by the starting rotation. Each of the 6 pitchers would throw 50 pitches, take two days off, and then return to the mound. That would cover the typical 100 pitch threshold that starters reach on a nightly basis.

More on tandem pitching

Check out this research paper on paired pitching from the 2009 SSAC.

Admittedly, Carleton is not the first person to suggest a restructuring of modern pitching staffs, or even the idea of "tandem" pitchers. What he does a fine job of, however, is outlining the benefits to a such a system, and highlighting some of the obstacles a team would have to overcome in implementing it.

Benefits

I feel that the ability to assemble a pitching staff on the cheap is the largest advantage to a system of paired pitching. The average salary for the 50 highest paid starting pitchers in 2013 is $13.5 million, a figure that many small market teams just cannot afford. The type of pitcher that Carleton suggests for this system (young pitchers, back of the rotation starters or even long relievers) would not cost nearly as much as veteran starters. In turn, teams would have more financial flexibility to address their position player and bullpen needs.

While cost is the largest advantage, keeping salaries down is only a minor win if the team on the field doesn't succeed. Fortunately, with this system teams can put together a competent staff while only making a small financial investment. Because pitchers are only throwing 50 pitches per outing, batters will only face them once or twice a night. It has been proven that batters have more success against pitchers with each subsequent time through the lineup, so limiting the times a pitcher has to face hitters should increase his effectiveness. To illustrate how some pitchers may perform in the system, here is the list of examples from Carleton's article with their xFIP in the first 3 innings versus their xFIP in the 4th inning or later:

Last season, the average xFIP for starting pitchers was 4.06, so all fifteen starters were above league average in the first three innings, while 14 of the 15 were below leave average from innings 4 on. And the numbers may be even better than that because the pitchers in the above table were pacing themselves to last for more than 3 innings, so their velocities may increase in shorter spurts. It seems plausible that a team could improve their results by switching to a tandem system.

Obstacles

I want to give credit to Russell Carleton for acknowledging that any radical change isn't without its obstacles. First question: is 50 pitches with two days off between outings a practical usage pattern for pitchers? It seems like pitchers would be able to handle that workload, but to this point we don't have any evidence for or against the theory:

At the MLB level, there are almost no examples of pitchers being used in a 50 pitches, two days off system. It seems like 50 pitches followed by two days off could work, at least in that it passes the smell test. If anything, this would require a complete re-conceptualization of how pitchers train and structure their workloads, and maybe it wouldn't work unless you've been pitching that way since the age of 12. The reality is that most pitchers train along one of two tracks, and so if a team wanted to implement this tandem model, it couldn't count on finding guys who were cast off from other organizations but already had trained in the same basic role the way that they can find six-inning starters. That makes searching for reinforcements a lot harder.

Pitchers, starters especially, are some of the most ritualistic athletes in any sport. They are creatures of habit and teams would be hard pressed to get many of them to willingly make the switch. Not only would pitchers need to adjust their routines, but many would be giving up the chance to earn wins by making the change. Currently a starting pitcher has to throw at least 5 innings in a game to earn a win, making it nearly impossible for someone throwing only 50 pitches to do. Although I think we can all agree pitcher wins are rather arbitrary, they still factor into award voting, salary negotiations, and Hall of Fame discussions, making them supremely important to the players. Getting players (and their agents) to buy into a system like this would certainly be the most difficult part. At least initially, a team may be limited to pitchers that are simply excited to be in the Major Leagues to try tandem pitching.

Another problem is the additional roster spot used by a pitcher. In Carleton's system, 6 pitchers are taking the place of a normal 5-man rotation, meaning that the staff as a whole will expand from 12 to 13 pitchers. Many think that modern pitching staffs are already too large, so I am not a huge proponent of using another roster spot on pitching. If teams elect to just go with a shorter bullpen, the effectiveness of each of those pitchers may decrease. I also have to believe that the system would also work much better in the regular season than in the playoffs, where pitcher usage is much different. While I think any team implementing a tandem pitching system should be thrilled to even make the playoffs, every team's ultimate goal is to win a World Series.

Lastly, undoubtedly any team to try this would have to deal with the criticisms of fans and media. We can applaud the Colorado Rockies for their decision to try a four man rotation last year, but ultimately the poor results (which certainly had more to do with the Rockies' personnel than anything) will only make it more difficult for the next team that wants to try a new approach to their pitching staff.

I think it may be a good idea, but I also think we are years away from seeing it happen. More importantly than what I think though, what does the BtBS community think about the idea of tandem pitching? Can it work, and how should it be implemented at the Major League level?