In discussing Phil Hughes’ injury this afternoon, I teased you all with a forthcoming post on Joba and the starting rotation, long a favorite RAB topic. What better time than after another 4.2-inning effort by one of the Yankee starters?

Before delving into the fun, let’s revisit tonight. Yanks score in the first and muster nothing offensively the rest of the game. Jonathan Albaladejo is worked well beyond any reasonable workload, and Chris Britton finally pitches in a game. Bad pitching, terrible offense, bad manager. The end.

So that brings to Joba Chamberlain. Currently, the Yankees are searching for answers out of the bullpen. They have Phil Hughes shelved with a fractured rib. Hopefully, he’ll return before the All Star break, but that seems to be a rather optimistic assessment. He’ll need at least a month of training and rehab after his month off for healing. Meanwhile, Ian Kennedy continues to struggle with his pitch counts.

But Joba Chamberlain’s eventually arrival in the starting rotation should happen regardless of the 2008 fates of Kennedy and Hughes. It really is just a matter of innings.

One month into the season, Chamberlain has thrown 11.1 innings in 10 appearances. The goal for him this year is to reach about 145 innings pitched or 30 more than he threw last year. That, according to a whole bunch of recent studies, should help him improve his arm strength without sending him into that danger zone of arm trouble. So how does Joba throw 133 more innings this year?

Well, let’s give him another 13 innings for May. That puts him needing 120 IP from June to September. For the purpose of this exercise, we can’t assume that the Yankees are going to make the playoffs. Outside of their lackluster play recently, Joba needs to be a position to reach 145 innings before the season ends. If the end of the year rolls around and the Yanks are in a position to play in October, they can begin to get creative with Joba’s turn in the rotation.

Now, luckily for us, the Yankees have a good benchmark for starts made in a partial season. We need to look no further than Roger Clemens to see how many innings Joba would pitch over a certain time frame. Between June 9 and Sept. 16 last year, Clemens made 17 starts and threw 98 innings in those starts, averaging 5.78 IP a start. He skipped a start in August and missed four in September. He also threw 15 Minor League innings over the course of three starts.

So now we can go back to those 120 innings Joba needs to throw over the last four months of the season. Let’s say he too needs 12 innings in the Minors covering three starts to stretch it out: one three-inning appearance, one four-inning appearance and one five-inning appearance. We’re now at 108 IP. How about three weeks of relief in June? That’s about 8 innings.

So Joba the starter would have to throw 100 pitches. If he averages around 6 innings a start — and there’s no reason to think he couldn’t — he would have to make between 16 and 17 starts. Using the Roger Clemens gamelog, it seems that Joba should land in the rotation right before the All Star break during the first week of July. If signs don’t point that way by the end of this month and the beginning of the next, then we’ll know something is up with Joba’s move to the pen. I think, however, that the Yanks will pursue this path.

Meanwhile, imagine if the Yanks get Joba into the rotation at around the same time that Phil Hughes makes his injury-free return to the Yankees. It would be like Christmas in July for us.