The above link (hopefully it works, if not there's always cut and paste) is to an interesting article that compares QBs across the league by their QB/PFF Rating when facing varied numbers of DBs. The first thing that jumps out, and this may not surprise too many of us) is that Andrew Luck has a better rating when facing more than 4 DBs.
Of course, the conclusions you may want to draw from this may depend highly on your opinion of PFF's ratings/analysis, so perhaps take the following with grain of salt.
Their rating of Luck v 4 DBs is -1.5. Versus 5 DBs he jumps to a +8.4. Versus 6 or more he's at +6.1. With any more than 4 DBs, and he's at +14.6. Of course, what Luck does is highly dependent on what the offensive line and openness of receivers allows him to, but at the very least, our offense appears much better when facing a greater number of DBs.
I'm no expert on formations for both offense and defense, but it would seem this should have implications for the number of receivers we put on the field. The more we can use WRs and TEs lined up in ways that take other defensive positions off the field and put more CBs and Safeties on it, the more we can utilize our strengths. Also, I would think decreasing our use of FBs would help (I can't imagine CBs cover them too often).