You never know what you're getting when you hire an assistant but Allen feels like a home run for IU. First, he's got the current team and the 2017 recruiting class lining up behind him so IU likely won't take the step back that many teams do when they change coaches.
Second, he's a likeable, charismatic guy who is an Indiana native, the son of Indiana high school coach, a former Indiana high school coach himself and someone who actually views the IU job as a destination job and not a stepping stone. This matters for recruiting and for the support he'll need from the fan base which is historically focused only on the starts of hoops.
And finally, he's proven himself an exceptional defensive coordinator both in his time at USF and in his one year at IU. He took the same guys that Brian Knorr had for 2 years and took them from the worst defense of any power 5 team to actual legitimate respectability.