Immediately eliminate Ellsbury. Too injury prone and only one season with top 20 production (I assume this is a 10 team league x 2 keepers). I would keep Tulo, even though he's also injury prone, for position scarcity, Coors Field, and top 10 production potential. The second keeper would be between Beltre/Gonzo. I like Hamels but you can toss him back into the draft and get good pitching if every team is only allowed 2 keepers. I'd probably lean towards Beltre for position scarcity reasons and ballpark factors although I do think Gonzo has a bounceback year this year. Good luck!