Four O'Clock Lightning

This is the play-by-play (from ESPN) of Mariano Rivera's disastrous 9th inning save attempt:

-Mariano Rivera pitches to Bill Mueller
-B Mueller walked.
-Mariano Rivera pitches to Mark Bellhorn
-M Bellhorn singled to right, B Mueller to second.
-Mariano Rivera pitches to Johnny Damon
-J Damon singled to right, B Mueller to third, M Bellhorn to second.
-Mariano Rivera pitches to Trot Nixon
-T Nixon struck out swinging.
-Mariano Rivera pitches to Manny Ramirez
-M Ramirez safe at first on error by third baseman A Rodriguez, B Mueller scored, M Bellhorn to third, J Damon to second.
-Mariano Rivera pitches to David Ortiz
-D Ortiz grounded out to pitcher, M Bellhorn scored, J Damon to third, M Ramirez to second. -Mariano Rivera pitches to Dave McCarty
-D McCarty walked.
-Mariano Rivera pitches to Edgar Renteria
-E Renteria singled to shallow left center, J Damon and M Ramirez scored, D McCarty to second.
-Mariano Rivera pitches to Doug Mirabelli
-D Mirabelli walked, D McCarty to third, E Renteria to second.

Some people think the Red Sox are in Mariano's head. Other folks feel that the success the Sox have against Rivera is due to the large number of times the two teams meet during the regular season. Me, I'm starting to wonder if there's not some physical cause for Rivera's woes. Is he injured? Or worse, at least from the Yankee's point of view, is the above a result of his skills being in decline? If I were more of a stat geek I'd look to see if I couldn't dig up some solid evidence of pitchers suffering abrupt (and permanent) declines in performance.