If it were only a few players who left, that would be one thing. But then there's this:
"Since the 2011-12 season, Mitchell has employed nine different assistants. This offseason is the second time in three years he’s had to replace all three full-time assistants."
Read more here:
Can Matthew Mitchell survive as UK Hoops coach?
If he can't even keep assistant coaches, whom he has brought into a top-tier SEC basketball program, then there is clearly something wrong with the head coach. That's certainly strike two- at least.
If I were AD, I'd reach out to the transferring players and the coaches who defected from the program to find out directly what was wrong. The head coach says that they all left for different personal reasons. But the AD should test that claim by finding out the truth.
In contrast, Coach Geno has never seen a single defection from one of his assistant coaches. Each has left to become head coach somewhere, and left with his blessing, and even recommendation to the hiring university.