In regards to Flacco and Wallace, in terms of wide receivers we have 8, which on paper sounds terrific. The problem is only a fraction of them have shown enough offensive production to be considered good weapons, them being Wallace himself and Perriman. Campanaro is decent but he's played in a total of 11 games in his 3 years here and only notched 2 TDs. Chris Moore has had a couple good catches but his only TDs were on special teams. Chris Matthews has only scored once in his entire career. Vince Mayle is on his 3rd team in 2 years. And both Kenny Bell and Keenan Reynolds haven't done anything.
Now it's entirely possible that one of those guys might be the diamond in the rough we're looking for, and that's the scenario we all want to happen. It's not a guarantee which is why picking a WR in the draft is more than necessary.