Ellsbury did hit .300, and have an OBP of .355 in 2009. I'm not saying he'll get right back to that, but those are perfectly good numbers for a leadoff hitter. He's also a good candidate because unlike Crawford, he doesn't have much power, and makes a lot more sense hitting from a spot where fewer runners will be on base, ie after Scutaro/Salty. Also, unlike the majority of the roster, he hits just as well on either side.