Funny you ask this ... I have found when playing the CPU, it is harder to run. I find I have to sometimes set the defense up first. On the 360, I didn't have trouble running.
Maybe it is in my head? ... but none the less, I think the running game in the PS3 version is more difficult ... IMO.
YES!! I'm not that terrible! Don't feel bad about juicing up your run blocking sliders.