From Crawford's comments yesterday it would appear that he felt like he ran less when hitting at the bottom of the order because he didn't want to make an out with the top of the order coming up.
I am inclined to agree with you, but that was his rationale.
But he has no problem making an out with the middle of the order coming up? File under, athletes say a lot of really dumb things.
Some people here are making a mistake of evaluating just the switch of Ellsbury from leadoff without evaluating the effect on the whole lineup. The way to think about this is that Valentine suggested that Crawford, Aviles, Ross, or Saltalamacchia should lead off. Only Crawford even warrents a serious discussion, and unless you're just flipping Ellsbury and Crawford, not only Ellsbury but many of the top five hitters will get less at bats and anything other than simply flipping Ellsbury and Crawford makes the L-R balance worse, not better (* see below). Unless Crawford is capable of replicating his 2010 season out of the leadoff spot, that makes no sense. Further, Crawford's 2010 season still might only make him the 6th best hitter on the team unless Ellsbury or Ortiz regresses (I pick them because they're probably the two highest probability regression candidates; Pedy hit at his established level last year, while Youk and Gonzo were a little below).
*Compare these top-6 options:
Ellsbury, Pedroia, Gonzalez, Youk, Ortiz, Crawford
Crawford, Pedroia, Gonzo, Youk, Ortiz, Ellsbury (only difference is the better hitter and basestealer is hitting 6th instead of first)
Crawford, Ellsbury, Pedroia, Gonzalez, Youk, Ortiz (none of your three best power hitters guaranteed to hit in the 1st, back-to-back lefties leading off, neither Pedroia nor Youk is as good a hitter as Gonzalez, but you need to break up the lefties with one of them)
The should spend spring training getting Crawford comfortable with the idea that he's not one of the best 5 hitters on the team, and therefore will not be hitting at the top of the order. (And yet they paid him $20 million a year. Ugh.)