Andersen had a 19-7 record during his two years and left the school in December after Mike Riley left Oregon State to take the head coaching position at Nebraska.
"It's been well [documented] there were some kids I couldn't get in school," Andersen said to CBSSports.com. "That was highly frustrating to me. I lost some guys, and I told them I wasn't going to lose them.
"I think they did what they were supposed to do [academically] and they still couldn't get in. That was really hard to deal with."
Andersen made it clear that he wasn't blaming Wisconsin for their standards.
"That's not Wisconsin's fault," Andersen said. "That's Wisconsin's deal ... I want to surround myself with those kids I can get in school."
In six seasons at Wisconsin and Utah State, Andersen has a 45-31 record.
Oregon State went 5-7 last season and failed to make a bowl game.
- Scooby Axson