I switched my dynasty with UAB over to Heisman mode. Games became more difficult, but I'm still undefeated (beat LSU by 1 TD coming from behind in the 4th quarter from 10 down. 17 unanswered points by the Blazers).
I've found a couple of things:
Mobile QB's are a huge plus. Being able to turn a busted pass play into a 5-10 yard scramble is a big plus.
Fast RB's, and strong FB's. The FB up the middle play in the goalline formation with a decent OL and a good FB is a good 3-4 yards nearly every time.
Counters out of the I-formation, and out of the single back double-TE set are good ones.
The best pass play I've found (but you need a really good WR for this one) is a play action pass out of the single back, double TE-set. Can't recall the name right now, but I run it for most of my pass plays. I can either hit the WR that angles towards the sidelines, or the deep WR. If both are covered, typically I can scramble for 5-10 yards. Not every time (sometimes they have a spy on me). But it's pretty effective.
Kicking is insane on heisman. I'm finally getting the speed down, but it's taking a while.
On defense, for teams that pass out of 3, 4, and 5 WR sets, I run dime defenses, mixing zone and man coverage. Typically, I move one of my DE's to the weak side. If they run where the DE was, they can sometimes break a decent run, but mostly, I either get a QB pressure or a sack.
Against running teams, I run 4-3 defenses where my outside lb's blitz. I bring the LB from the weak side up to the line on the side of the DE. This gives him a better jump on the snap. This seems to work better on the right side than on the left. I guess RT's are smarter than LT's in 2005. *shrug*
So far, I have two games on Heisman that made my list of greatest games. I've only had two blow outs (one against Vanderbilt, and one against Arkansas), but nothing on the scale of AA mode. So far, my WR looks like he'll be a heisman winner, with my QB in second. (My FB, who gets lots of TD's, is in 4th or 5th place.)
Building a strong DL, secondary, OL... those are the most important positions. If those are weak, all your other positions are irrelevant. I recruit strong DL and OL even when I don't need them. QB, RB, and WR... lastly LB. A good K and P are good to have, but I have little control over kicking in Heisman at the moment, so it's irrelevant how good they are until I get better.