Lineman on lineman impact is generally not that impactful Been a while since I've read up on this but http://mmqb.si.com/2014/10/14/new-harvard-study-concussions-in-the-trenches http://www.cleveland.com/science/index.ssf/2013/03/non-concussion_football_head_h.html So....I guess if their technique is "good" enough (however realistic that may be in practice) to avoid bumping helmets often, sure. I'm not sure how realistic that may or may not be, but with 9+ guys involved I could see it happening fairly often. Probably not every play, though.