I was watching my preseason game when this play occurred https://usflwfl.myfootballnow.com/watch/5793#1052154. Jeffrey Dahmer is a SLB yet he was lined up on the defensive line. The play call was 4-3 Under Wide Line, and it calls for the SLB to basically be a 5th DL.

I'm not even attempting to restrict which plays get called, so if a defensive alignment calls for a LB to be on the line, it's legal.

Thats why I love the defensive line restrictions on weight...you can blitz LB with the right defensive call so putting LBs on the defensive line isn't needed to create mismatches.

Overuse the play call will have penalties so use it wisely