You don't have to sell me on the importance of defense. I am a strong proponent of good defense, despite my support of Hanley's signing.
I don't think the FO took LF lightly. I just think they really believed Hanley would be "adequate", meaning he wouldn't be a great liability. We have not had strong defenders in LF recently with the likes of Manny, Bay, and Gomes, and the team has overcome that just fine.