I used to do cb blitzes but those can give up easy first downs if they run up the middle or see that the cb blitz is coming n they arent running to the outside (since you can't bring ur safeties over to their wrs before the play because then theyd know it was a cb blitz)......I like running a simple cover 3, and usering my DE on the weak side (or the opposite side i think they are going to run to).....even if they pitch to the weak side, atleast your DE isnt wrapped up in a block, and he can freely roam to the outside to either contain or tackle the RB. Hope this helps its a simple way to stop it without running a full force outside run blitz.