People have already covered it, but Spikes could not make the move. There is no reason to think that he'd be an especially good pass rusher on the outside. Also a different world from going to playing in space as a MLB, to playing a great deal on a TE or at the LOS.
Spikes is fun to watch at times, but he's not overly good at taking on blocks and he's not overly fast as evidenced by his times. He plays faster than his times, but he's not going to be running down running backs in coverage or even some of the faster TEs.