Let's be clear, Penning isn't just a little more aggressive. Dude has an old-school brawler mentality that was seen as both a strength and a weakness because some scouts were worried he wouldn't be able to rein that in in the pros.
Yeah, I think he might have gained some wisdom after going a bit overboard during Training Camp last year, that just maybe maintaining health during the season is more important than pummeling his own teammates after the play is over.