BOSTON -- Andy Pettitte's comeback is rapidly changing from "this could be interesting" to "this could be absolutely necessary."

There is no overstating Pettitte's achievements or his standing in the world of the Yankees. But when he announced in mid-March that he was ending his one-year retirement, the Yankees appeared to have a surplus of starting-pitching candidates, as in seven for five spots.

But now, it appears that the Yankees might be looking at a deficit, rather than a surplus, in the rotation. Pettitte's return, seen not that long ago as a potentially pleasant sidelight to the 2012 season, now looks much more like a requirement than an elective for the Yankees.

In the interim, hard-throwing Michael Pineda went on the disabled list with right rotator cuff tendinitis. The Yankees paid a steep price, trading a blue-chip hitting prospect, catcher Jesus Montero, to get Pineda from Seattle. But at 23, Pineda was projected to be a staple of the Yankees' rotation for years to come. Well, maybe later.

There was bad news this weekend on Pineda's rehabilitation. Yankees manager Joe Girardi said that Pineda had to cut short a start in extended spring after once again feeling discomfort behind his shoulder. Pineda threw only 15 pitches in the outing.

"I think it's somewhat significant, just because you were expecting him to build up," Girardi said. "Now, you're going to have to give him probably a little bit more time than we did before. I can't tell you when we'll get him back now."

The "I can't tell you when we'll get him back now," sets off alarm bells for those who have been paying attention. In the visiting manager's office at Fenway Park on Sunday, shortly after the Yankees-Red Sox game was postponed due to rain, Girardi said that Pineda was scheduled to be examined by Yankees doctors in New York on Monday.

But Pineda's shoulder problem was not the only cause for rotation alarm the Yankees had this weekend.

Freddy Garcia was hit hard on Saturday by the Red Sox, giving up five earned runs on seven hits in just 1 2/3 innings. The Yankees subsequently staged a comeback for the ages, rallying from a 9-0 deficit, scoring seven runs in both the seventh an eight innings and eventually prevailing, 15-9.

But that didn't make Garcia's outing any more acceptable. Garcia pitched more than capably for the Yankees in 2011, but his three starts this season have offered little indication of a repeat performance. His ERA is now 9.75. There is a small sample size involved, but Garcia will be 36 in October, and Saturday, his fastball velocity was in the mid-80s. If he doesn't have command of his secondary pitches, he isn't going to succeed and that command has not been consistently present in his first three starts.

It is relatively easy to imagine Pettitte being better than this. But no matter how much Pettitte meant to the Yankees as an integral part of five World Series championship teams, there will be some question about how much can fairly be expected out of a pitcher who will be 40 in June and who has been out of the game since 2010.

The Yankees have been encouraged by Pettitte's work on the comeback trail. Pettitte threw 58 of 66 pitches for strikes in an extended spring game Friday. Girardi said that Pettitte would start Wednesday for Double-A Trenton and would be expected to throw 80-85 pitches.

"It's getting close to reality now," Girardi said.

Girardi further suggested that Pettitte could be three Minor League starts away from returning to the Yankees.

"I think that's realistic to look at -- three more Minor League starts, and then you make an evaluation of where he's at and what he needs," Girardi said.

What the Yankees need is more consistent starting pitching. The overall performance of the rotation so far could charitably be described as uneven. After three turns through the rotation, only one starter, Ivan Nova, has an ERA under 5.00. The substantial track record of a pitcher such as CC Sabathia or Hiroki Kuroda suggests much better, more consistent performances are a matter of when rather than if.

But overall, reinforcement may be needed. The fact that the Yankees are 9-6 despite the starting performances is a tribute to a relentless offense and an effective bullpen. But the winning combination at some point will have to include at least competent starting pitching.

So the comeback attempt of Pettitte is no longer a curiosity. This is a man with 240 Major League victories, not to mention 19 postseason wins. Can he pitch at something resembling his previous level? Even as age 40 closes in? While trying to clear away a year's worth of rust? This is far from a given. But for the Yankees, Pettitte's comeback has gone from being perhaps a pleasant add-on to being potential help in an area where help is really needed.