I tried this a couple times. The first time, in my very first season, I made a couple of QBs, a Senior and a Freshman. They were both ranked in the top 10, and I got them both even though I was rebuilding KU, who was horrible. I lost in the National Title game the first year to Alabama, and haven't lost since. The Freshman kid is now a Junior, and was sure to win the heisman and go pro, but with 10 weeks to play he broke a collarbone and is out 11 weeks. So I don't know if I'll have him next year or not. I'm enjoying playing with my backup QB more since he's not nearly as good.
However, the second season I tried creating a stud DT. He was a beast, with like a 98 rating as a Freshman! Problem was I couldn't get him, and he went to OU, so now I have to play him once or twice every year. - ha.
Anyway, I decided it seemed like cheating, so I haven't created recruits since, and only play with the talent I can recruit from around the country.