I know my Notre Dame brethren will back me up on this. But as a ND guy who watched every snap that Jaylon played in college he is a much better LB than rusher.
What Jaylon did for our defense, and we didn't have Alabama talent, was completely take away the middle of the field. Jaylon's speed and athletic ability took away crossing routes, limited check downs, and forced teams to work outside of the hash. That in turn allowed us to flood those areas and cobble together a pretty good defense. I suspect that next year, after he's fully healed, Marinelli will use him as the deep middle LB in a Tampa Two.
FWIW, Jaylon didn't play MLB at ND. A guy named Joe Schmidt did. Joe was our Sean Lee. He knew the defense cold and could get everyone lined up correctly. So he called the defense and Jaylon played to his side.
As a pass rusher Jaylon's move was speed and coming off the blitz. At ND it just wouldn't have made sense for ND to play him at DE. At DE teams could have schemed around him. At MLB you couldn't really scheme him out of games.