In December, Alex Rodriguez flew to Germany* to receive platelet-rich plasma therapy on his right knee and left shoulder. Most of the evidence supporting the benefits of PRP is anecdotal though. One scientific study suggests there is little to no benefit of PRP compared to regular saline solution. But A-Rod apparently went on the advice of Kobe Bryant**, who had the therapy twice last year with the same German doctor. If we're going to believe it worked for Kobe, it would be natural to think there'd be an improvement in his stats. There isn't. He's averaging virtually the same number of points, rebounds, assists and steals (per 36 minutes). He is playing about five more minutes per game, but he's only played 27 games, so we have yet to see if he maintains that for another 55 contests (FYI, he played in all 82 games last year, so health wasn't much of an issue, making it tougher to claim PRP made him healthier).
Before A-Rod ever flew across the pond, the Yankees checked with MLB and WADA (World Anti-Doping Agency) on the permissibility of the therapy (after all, A-Rod's had illegal and semi-legal procedures in the past). They both OK'ed it and off he flew.
Unlike Bryant, A-Rod did have serious injury issues last season. He played in only 99 games (and hasn't reached 140 since 2007), had his worst season (via bWAR) since 1995(!) and has declined each of the last four seasons. If anyone needs this therapy to work - not only to keep him healthy but to improve his game - it's A-Rod.
Was he merely unlucky last year? The peripherals says no. His BABIP (.311) was right in line with his career average, but he had his second worst line drive rate (only worsted in 2010), highest ground ball rate and lowest fly ball rate since at least 2002 (since that's the furthest FanGraphs batted ball stats go back). The only years in which he had a lower IsoP (Isolated Power) were 1994 and '95, his first two years in MLB.
There is a little light at the end of the tunnel. He maintained career averages in BB and K rates, so he's at least seeing the ball fairly well, but it looks like, although his eyes still retain their sharpness, his body isn't responding as well as it used to. The pitch value numbers seem to back this up: A-Rod had trouble with fastballs in 2011 (as well as cutters, curves and changeups), having his worst season against that pitch since at least '02.
At this point, we just have to hope PRP therapy works, because the Yanks can't afford another declining year from A-Rod, especially with six left on his contract. If Kobe Bryant - or, you know, actual medical studies - are any indicator, don't get your hopes up.
* Because that's apparently where the world's best in this procedure is.