For the first time in a long while, the Red Sox have a bona fide positional competition on their hands -- if Coco Crisp isn't traded, that is. With Jacoby Ellsbury having the inside track to be the starter in center field after last October, the Red Sox may enter the season with only one of the two center fielders on the roster. Or they might enter it with both. We look at how the two stack up in four categories, and let you vote for which you think should get the nod. (Text by Globe Staff)