Arod has never been likeable and has never been popular with the Yankee fans, except until recently because he's viewed as the subject of a MLB witch hunt. Exhibit A: trying to knock the ball out of a Boston fielder's glove during the 2004 Pennant Series, the Esquire article and pulling that stunt against the Blue Jays.
For Ortiz, it's just the reverse. Whenever I've seen him, it always seems like he has a smile on his face and is enjoying himself. I even got a kick out of his applauding that great play made by the Tiger 2B or SS (can't remember which) last week.
As in the game of life, a smile, a good attitude, goes a long way.