NASHVILLE, Tenn. -- The Yankees did not receive the production they expected from Alex Rodriguez in this year's postseason, and manager Joe Girardi now feels confident that he knows why.Rodriguez is heading for arthroscopic left hip surgery, a procedure that could require four to six months for recovery, forcing Girardi and the Yankees to move forward with a big hole to fill at third base. "It probably answers a lot of questions," Girardi said during his Day 2 news conference at the Winter Meetings on Tuesday. "He wasn't the Alex we saw before the injury, and now we have a reason possibly why. Alex could have bowed out and said, 'I'm not going to play,' or 'This is what it is,' but he kept playing. "He kept trying to be productive for us. Obviously, he wasn't even sure what was going on. But he knew that his hips weren't working the way he was accustomed to them working." Girardi confirmed a timeline of events provided on Monday by Yankees general manager Brian Cashman, who said that Rodriguez's first complaint of an injury -- originally thought to be to his surgically repaired right hip -- came in a dugout conversation during the American League Division Series. "When I told him that I was going to pinch-hit for him, that was in Game 3," Girardi said. "He had told me that he and [hitting coach] Kevin [Long] were talking, and basically he just felt his hips weren't firing right. It wasn't pain, but he just felt there was not the explosiveness. "We sent him out for an MRI, I believe it was the next day, but it was on his right hip, and that came back fine. So I kept playing him. Little did we know it was his left hip, we found out much later, and now we're at the point where he needs surgery, and we're going to be without him for a substantial period of time." Girardi said that he expects Rodriguez to return to the Yankees' lineup in 2013, but acknowledges that the three-time AL MVP could need to see increased duty as a designated hitter. "He'll have to DH some," Girardi said. "That's one way of getting him back in the lineup and working him back into playing shape. I hope I get to make that decision in June. That would be really nice." In the meantime, Girardi said that the Yankees do not have a strong internal option to take over for Rodriguez. Prospect David Adams saw time at third base in Triple-A and in the Arizona Fall League, but Girardi noted, "We don't really have anyone that has a lot of experience in that position." Girardi suggested that the Yankees may wind up with a platoon situation at third base, possibly including veteran Eric Chavez, a free agent the team has shown interest in retaining. "We talked about that. If it takes two guys to fill that spot, it takes two guys," Girardi said. Girardi said that he was pleased by the completed deals to retain pitchers Hiroki Kuroda, Andy Pettitte and Mariano Rivera, noted that CC Sabathia's rehab from elbow surgery is "coming along great," and envisions the No. 5 starter job to be a competition between David Phelps and Ivan Nova. He also said that he is not concerned that the Yankees haven't been able to fill their other position-player holes. Cashman continues to seek a right fielder to replace free agent Nick Swisher, as well as a potential upgrade over the current trio of catching options after losing Russell Martin to the Pirates. As it stands now, Girardi said that he anticipates the catching picture -- with Francisco Cervelli, Chris Stewart and Austin Romine vying for playing time -- to be an open competition this spring. That means it is too early for Girardi to begin thinking about his lineup, and probably too soon to get attached to the roster as is currently comprised. "I think I've gotten used to seeing moves made fairly late, and I know from the internal discussions that we had, that we're going to have people in place by the time Spring Training is here," Girardi said. "Of course, everyone wants to know right now, what are the Yankees going to be, and who are they going to be in 2013? But I don't get too worried about it."