(AP Photo/Michael Dwyer)

The question comes up frequently, but we’ve yet to explore the possibility fully. The Yankees still seek a starter for their 2012 rotation, and there doesn’t appear to be much available on the market. While they have five starters in name, plus a few young backup plans, adding another mid- to upper-rotation arm will only help them in their quest to win the AL East and more. As many have asked, might David Robertson make sense in that role?

Why tackle this now? For starters, the Winter Meetings are going slowly for the Yankees, and things don’t figure to pick up. Maybe the Yankees have something on the horizon, but if they do it will come as a surprise to everyone. Meanwhile, we still enjoy exploring all reasonable avenues of improving the team. Also, Marc Normandin of Over the Monster recently wrote about Daniel Bard as a starter. That created the opportunity to piggyback some of the great work he did there.

While Marc’s work on Bard inspired this article, Bard might not provide the best comparable for Robertson. After all, Bard started game for UNC before turning pro, and then spent his first minor league season in the rotation. He’s been a reliever ever since, but at least he has a history of starting games. Robertson, on the other hand, has no such history. The last time he started a game was in 2005 when he was still hurling for Alabama. Since then he’s been used exclusively in relief. This makes him a bit more like Alexi Ogando, who had no starting experience prior to 2011. Then again, he had little pitching experience at all.

One big consideration in making a move is the translation between starter and reliever. That is, a pitcher will likely pitch better in relief for a number of reasons. Tom Tango applies what he calls the Rule of 17 for estimating these translations. Essentially, there are three factors that change by 17 percent when moving between the rotation and bullpen: strikeouts per PA, BABIP, and home runs per contact rate. What catches the eye, and what works to Robertson’s great benefit, is that walk rate doesn’t change much at all. He can’t really afford to walk more hitters than he already does — his almost 90 percent strand rate greatly aided his 2011 campaign — so any change in transition to the rotation would not be welcome. But if it remains flat, perhaps he can make it work.

If we use only Robertson’s 2011 season, clearly he’d look superb as a starter; his results were off the charts, both in terms of peripherals and results. There’s only a minuscule chance he can approach those numbers again in relief. Still, he did have two quality seasons in 2009 and 2010, following a rough rookie campaign in 2008. If we add up all his innings, though, he’s at 202 for his career. Since that’s a full season, it might be best to apply the Rule of 17 to his career stats and see what we get.

There are a few caveats to attend here. First, Tango’s study encompassed all pitchers. Some performed better than this baseline, some performed worse. It’s tough to know where Robertson will fall on that curve. It’s unlikely, for example, that he’d have a .373 BABIP as a starter. Even though pitchers do have a degree of control over the types of contact they induce, .373 seems out of line for anyone. This is all part of the great unknown of this whole experiment.

Also a factor: Robertson’s discernible improvement in 2011. It wasn’t just in the results. Robertson added about a mile per hour to his fastball. This played a large role in his heightened strikeout rate, as did the “sneaky fast” nature of his fastball; that is, it gets on top of hitters faster than they might expect, thanks to his extended stride. There is a chance, then, that some of his improvement could be real, and could make his expected numbers look even prettier.

The one thing that could hold back Robertson is his repertoire. While he does have two quality pitches in his fastball and curveball, he doesn’t quite have that third pitch. He’s used a cutter, which has been effective at times. He also uses a changeup, but not at all frequently. He’d have to drastically increase its usage in the rotation. It’s not that using his changeup more frequently is out of the question; he really doesn’t have a chance to use a third pitch in the bullpen, after all. It’s that the third pitch adds another level of uncertainty to the conversion.

Finally, we have the issue of innings. Last year Robertson threw 66.2 innings, his highest total as a major leaguer. His previous high came all the way back in 2006, when he threw 82.2 innings combined between Alabama and the Cape Cod League. This is where a comparison with Ogando might work. In 2010 he threw about 75 innings between the minors and majors before making the jump to 169 innings in 2011. He did tire down the stretch, too. The Yankees couldn’t expect more than that from Robertson. It’s also unknown how Ogando will rebound from this increase in workload. He didn’t hurt himself in 2011, but there is still risk in the following year. Fatigue leads to poor mechanics, and poor mechanics can lead to injury, both in the present and in the future. The Yankees probably don’t want to take that risk with one of their best bullpen arms.

There certainly exists a case for converting Robertson to a starter. He took a significant step forward in 2011, and there’s a chance that his talents could play up well when throwing six, seven, or eight innings an outing. There are, unfortunately, a significant number of unknowns, uncertainties, and risks that go along with such a conversion. The Yankees are aware of these, I’m sure, and I don’t doubt that they’ve mulled the possibility, if only casually. It’s not a terrible idea in theory, but everything would have to break the Yankees way for it to work out. It’s understandable, then, if they wish to keep things as they currently stand. Robertson is plenty fine in his current role.