Defensive line is one of the easiest positions on the field to learn. Honestly, possibly the easiest. We are very simple creatures. See ball, get ball. You pretty much need to hear one single word in the huddle to be told where to line up and that’s it. For stunts/movements/blitzes, you already know all the patterns from past experience, so you just have to quickly calibrate to what the new team calls them. And there are plenty of little cheats built in to learn quick. Exit = End goes first, tackle wraps. Tex = Tackle goes first, end wraps. One team may call it Ears & Thumbs instead of Exit & Tex. Easy switch to learn. And if all else fails, you just ask the guy next to you. But in reality, DL is very simple to learn the alignments and assignments. It’s the technique and execution that’s the difficult part. But a guy like Jeffrey Simmons has zero problem with that obviously, that part is the whole reason you bring him in!