Per Ohio.Com UA running backs coach Reno Ferri handed in his resignation to the Akron board of trustees, who accepted it. This is about two weeks after he was placed on administrative, paid, leave for alleged, and still unspecified, recruiting violations.
It's likely that any violation(s) that may have occurred were not serious and it was merely the state of Zips football as a whole (2 players suspended, one for a criminal offense) the led Ferri to leave the team.
Folks who are as 'in the know' as could be expected from fans over at zips nation seem to think the problem was merely a secondary offense.