Not every play is one in which the corner should turn and look back for the ball. In some circumstances, doing so may slow the corner down or cause him to lose track of the receiver.
Also, VT's DBs are (in some circumstances) taught to simply "punch the pocket" -- to dislodge the ball rather than turn their head, try to acquire the ball in the air, and make a play on it.
Again, of all the things to criticize VT football about, I don't think the play of the secondary is the thing. I mean, they lead all of college football in INTs in the Bud Foster era.