Malcom Floyd is much > than Boldin in my opinion. I'd rather have Rivers throwing than Flacco. Floyd is top 4 WRs in Fantasy right now. He is the lock on WR 2, not Wallace.
I would say its really between Boldin and Wallace in which I tink Wallace is the more exciting and higher upside guy. Baltimore is going to be running alot and may infact go deep to Boldin but Big Ben is out to have 6 games in 1 this week, Wallace has the biggest upside albeit a minor minor slightly riskier play than Boldin. Almost the same floor, higher ceiling with Wallace.
Austin, Floyd, Wallace, Boldin (last two interchangeable depending if you want to go safe or highest potential points)