I think it is a combination of both...coaches realize that passing is a better way to move the football, because the rule changes have made it that way.
Sal and Jeremy had a pretty interesting discussion this morning about how dramatically passing stats have gone up since 2011, with the CBA, and rule changes that were introduced then. They were speculating that, if healthy, the way the game is now, more than a handful of the current young QB's may very well supplant Drew Brees as the yardage leader...it is the way the game is trending.
I love a good shootout, but to be honest (warning: old guy take) I am getting a little numb to them. Granted, if I wasn't a Bills fan, I likely would have found the Bills/Titans game kid of dull, I am not so sure it would have been much duller than the Saints/Redskins game on Monday Night.