MOST VALUABLE PLAYER
Definition of valuable: useful: of great importance or use or service.
Which player is more valuable to their team? Remeber it's not who's the best hitter, or the best all around player ... it's who has the most VALUE to his team.
The Red Sox sit in first place right now with Papi in the lineup. The Yankee currently sit in 2nd and are out of the playoffs. If Ortiz was taken off the Red Sox, Manny Ramirez would be Barry Bonds, and we would more than likely not be in the playoff hunt. If you took Arod off the Yankees they would still be 2nd, possibly 3rd in the division, and really in no worse shape than they are now, out of the playoffs.
If you look at it that way it's obvious that Ortiz is more valuable. Not only does Arod have more money around him, but he also has Shitfield, Matsucki, and Steroids, who all hit for power, and could pick up the slack and still leave the team with a very potent offense. Ortiz is the heart and soul of this offense, IMO, and losing him would be devastating.