Late in the game, Baker was shooting free throws. When a player is to shoot free throws, the substitutions occur AFTER the first free throw. If there are any additional substitutions (such as substitutions for the shooter), those can also occur after the second free throw.
KY subs Hall out after the first free throw. But then he attempts to sub Hall back in for Baker after the second free throw. However, since Hall had been substituted out, and no time came off the clock, he was not allowed to sub back in.
I have to imagine that KY knew this but that he also knew it would stop play and prevent VCU from executing a quick inbound.
Not a huge deal but something subtle to allow our guys a few extra seconds to get set and prepared on defense.