What's the Deal with Mariano Rivera's Non-Save Struggles?

Friday's night game versus the Halos gave us another example of how Mariano Rivera seems like a different pitcher when brought into a non-save situation. The great closer is enjoying one of the best years of his sure to-be hall of fame career, but he has been worse than ever when he enters the game for any reason other than a save opportunity. It was a tied game in the ninth and Girardi called upon his closer to hold the game at a tie. He entered the game and proceeded to walk the lead off man. The walk was just his fifth walk issued all year. A single then led to runners at first and third and Tori Hunter soon after singled in the go ahead run. No one really has the answer to such a thing. Rivera has been perfect in nailing down all 26 save attempts this year but has been far from perfect in other situations. Rivera sat in front of his locker after that game a loss for words only to mutter the word, "unacceptable." "I wish I could explain it," Rivera said. "I wish somebody could explain ... (link)