I don't see the lapse in judgement of signing a player who has been pretty healthy for quite a few years. Its not like he got hurt from a pre-existing condition, kidney stones happen.
He was the best outfielder available at the time that didn't cost a 4+ year, 65 mill+ contract. The other options were Jermaine Dye who can't field, Nady who took most of last year off, Marlon Byrd who wanted a longer contract and was mostly unproven, and Damon/Crisp and the list only gets worse. Yeah, I wanted Holliday, but they chose Lackey instead.