Pedro Martinez predicts that he will return to the Mets during the second half of the 2007 season. He also predicted he would return a stronger pitcher. "Without a doubt I'm supposed to come back by the second half of 2007," Martinez told the Daily News yesterday afternoon at Shea, in his first comments since shoulder surgery six days earlier. "I'm going to work my tail off and get better. I'm actually feeling better right now - already. I'm very optimistic that with hard work, which I know how to do, and with the proper rehab, I should be right back. And I'm supposed to be better than I was." Martinez had surgery last Thursday to repair a torn rotator cuff. GM Omar Minaya estimated an eight-month recovery period.