"Sign a guy whose Career is based on his legs to a contract that lasts until he's 35."
Well he's 30 now and would only be 33 at the end of the guaranteed 4 years. He also hasn't really had any injury issues. Juan Pierre is 35 and just stole 37 bases last year.
"Bourn isn't that good, and tying up our limited funds into an aging OF whose overrated is not smart."
You can feel free to call him overrated and not that good but it's entirely opinion. Considering the other contracts handed out this offseason, it seems he isn't at all overrated. If Bourn is what we're going to call an aging OF, wait till next offseason when the best options consist of players either even older or far more injury prone: Ellsbury (30), Choo (31), Morse (32), Murphy (32), Hart (32), Cruz (33). What do we call them?