I don't think a lefty reliever is a big priority. Rolison has been death on lefties, Thielbar's step back has mostly been against RHP, Webb's a reverse splits guy, etc. I would certainly not poo poo a reliever the caliber of Morejon, but I'm much more worried about late matchups against RHH as opposed to LHH. Like right now this second if you need to get out a tough righty your best bet is Tyler Ferguson?
I think you need a closer or closer adjacent arm, and then IMO you'd like someone with some serious juice on the fastball who is tough on righties (Johnny Lasagna is having a resurgence woth AZ?). I also, while it didn't work out, wouldn't hate another Jose Cuas type trade where you acquire someone optionable. One of the writers threw Victor Vodnik out there and I'd be into that. If Tommy can fix him on the fly awesome, if not he's Iowa depth and a guy you hopefully can fix over the offseason.