I'm assuming this is a 2 QB league since you have the 2 listed right? If so then I think you are fine with Shaub and Cutler but you'll need someone later as a backup (Vick won't cut it)!
I don't think Ronnie will be that bad....in fact I think he will be pretty good this year so I would stay put there.
I think you could use a better WR3 instead of Mason but since it's PPR then he might surprise you since Flacco has looked good and it looks like they might throw more this year in Balt!
I think the only thing I would do really is try and get a better fill in QB, a better WR3 if you want to, and upgrade Ronnie if you want to try but......none of this is absolutely neccessary......your team is pretty good they way it is now!
Standard H2H 12 Team 1 Pt PPR, Start 1QB, 2RB, 2WR, 1 FLEX (RB/WR/TE), 1TE, 1K, 1 DEF