The Tennessee basketball program was basically dead when Bruce Pearl came in (who isn't even that great of a coach) and restored Tennessee to a top 25 program within three years. If you hire the right mid major guy, and if you are smart about it, it's not that hard to starting winning again.
Will the recruiting improve? Yes, but not as much as you think. Tennessee basically got the 60 year old version of Cuonzo Martin.
Actually, that's unfair to Cuonzo, because he's actually been to a Sweet Sixteen this decade.