I love the 34, that said I agree some aspects of the 34 are broken.
I have stuck with it and have learned how to use it quite affectively against the cpu as well as on line.
Since your real football experience would indicate your understanding the concept I can offer some tips which you may already be using regarding using the 34 against the cpu.
Start by looking at your next opponents off playbook. I consider this to be like looking at game tapes, also, Madden 12 does a pretty good job of mixing things up so it won't play out as if you got a copy of your opponents gameplan.
This will give you a clear idea of your opponents tendencies. This will also give you an idea of how and when to make line shifts/stunts and how to adjust your LBs pre snap. I adjust 1 to 3 LBs individually as the game only allows gap adjustments/shifts as a unit. Takes some practice to make your adjustments quickly but it can be done and is very affective.
Make use of sub packages to create mismatches.
User the MIKE or WILL the most and play the run!!!! CPU has a tendency to run to the strongside, until I figured this out I was consistently getting gashed for huge gains. Sound familiar???
Try to have your other ILB in hook zone or spy if he is not assigned to RB or blitzing. This will limit big gains on Draws.
Whenever the play calls for MIKE and WILL blitz, move the ILB you are controlling back some, this will give you a clearer path into the backfield as other players are engaged, also gives you more time to react if the play goes away from the blitz or you have to pick up the checkdown.
Good cpu QBs will send a reciever into the area vacated by ILBs if you do this a lot, so mix it up some, put one of your ILBs in hook or spy from time to time on MIKE/WILL blitzes.
Sometimes I will user the Jack or Sam on blitzes. On occasion the OFF will present you with an opportunity to grab an OLB assigned to zone and blitz instead. You will recognize it when it happens, very affective.
Moving/spreading your SAM or Jack or both of LOS and into space can often provide them with better angle to ballcarrier and more time to react to play/less likely to get sucked into blocks.
I don't use nano's, I mostly stick with the plays as designed except for an occasional switch to zone/spy and blitzing an OLB from zone when opportunity presents itself.
All of the above works against humans as well except you have to recognize tendencies in game.
Try to stay of the sprint button until you have a clear path to the ball or when in coverage.
I strongly recommend adjusting your priority and position style settings for user vs cpu games. At the least this will somewhat nueter an overly effective 34 Dline and allow your LBs to lead in tackle stats and flow to the ball much more realistically. Details can be found in
"Examining franchise elephant in the room" as I can't get the link to work for some reason.