You probably want to post over in sliders forum to get more feedback and ideas. For now let me see what I can do to help:
1. Before we even get to sliders, M11 offered some facets of the running game that IMO were more real life than in the past. Points to keep in mind: a. Don't touch the sprint button. The Defenders come off their blocks faster when you do that. Hit sprint only in open field.
b. Follow and read your blocks. You can't just go to the spot where the hole is supposed to be. Be prepared to cut in sooner or bounce out. Know what the key block is on every running play and/or where the double team block is. You usually want to cut off the double team.
c. Use play art to look at the blocking scheme. I've noticed for example that I'm in single back formation running a dive and the NT is double teamed but the LB is unblocked! Going ahead and running that play is suicide. To the game's credit, that unblocked LB is usually going to stuff you at the line. Audible to something else, flip sides, whatever but make sure the front 7 guys have a man on them (unless it's an outside guy...sometimes you don't have to block them on certain plays.).
d. Audible......just like in real life if you call a running play and they've got 8 guys in the box, continuing to try to run against that isn't going to work. Audible to a pass play (but watch for blitzers, get rid of the ball quick). IE. I was playing as the Steelers against the Jags the other night and was looking forward to a nice ground and pound game. Well the Jags continually came out in 7 and 8 man fronts making running really tough. I started calling pass plays from 3-4 WR sets to force them into other defenses less run oriented. When they finally did (I had to throw way more passes than I intended) I could audible to a run against a 5 or 6 man front and have more success.
e. Know your blockers ratings. If I'm the Vikes it makes far more sense for me to run left with Hutchinson over there than to the right. Study your roster, know who the good run blockers are.
f. By the same token, know the D. Trying to run at Suh all day is a waste of time.
These are just real life issues to deal with running the ball. This game to it's credit is not just an arcade game where you can run with impunity. I have games where I get destroyed running the ball too. But most of the time my back ends up with a tidy 4 ypc average (like 21 carries 85 yards etc.).
2. Regarding sliders......you'll get all sorts of advice as to which ones are best or best for you. I can say this: Lower the cpu run reaction, tackling, and block shed.....and/or raise human runblock, and break tackle. In the beginning, I had to make it easier for myself to have any running game at all. As I got better (and smarter) I was able to lower the sliders back to a more challenging level.
Hope this helps and post in the slider forum for more help on that.
PS.....I have my own set of sliders that work for me. It's on all madden though. Maybe check my numbers, and those of other sets to get an idea of what you may want to do. At all costs avoid Jarrod's set....He's totally insane and even looking at his sliders will set your running game back 3 levels.