Looks like there's a ton of speed available, but you've already got Crawford, Reyes, Victorino and Posed. If speed has been an issue, you can't go wrong with Pierre.
Looks like your biggest weakness is Aaron Hill at 2B, and I'd even consider replacing him with somebody like Beckham or Neil Walker.
For the best overall pickup. You can't go wrong with Luke Scott or Hunter Pence, but in my opinion, you should grab Chris Johnson. He has been ridiculous over the past month and you should ride it while you can.