14 passes, that's very efficient. One thing I notice (although I was nowhere near painstaking) is that some of the games in the higher end of the scale involved pretty good rushing too. In other words, if the rushing is strong enough to be a threat, it makes it easier to be efficient with your passing. The '96 Rice game comes to mine. We only threw 15 passes, but we scored 49 points.
So, I guess what I'm trying to say is that even though PED is the most important statistic, you couldn't abandon other aspects of the game and pin everything on throwing well and defending the pass well.
I had a little league basketball coach who had spent some time keeping stats. He discovered that the team that shot the ball more nearly always won. His interpretation was that would should shoot any time we had a reasonably good shot. In little league, it may not have been bad advice (since passing it around more could lead to turnovers). But at higher levels, you realize that the team that shoots the ball more also probably won the turnover battle and/or the rebounding battle (and possibly fouled less). In other words, the greater number of shots doesn't result from the coach greenlighting his team to shoot, but from playing good defense, taking care of the ball and rebounding (again of course assuming no huge disparity in fouls).
So an important question then becomes, what factors other than passing influence the PE number on offense and defense. For example, if you completely stuff an opponent's running game, it will likely lead to more 3rd and long situations. Typically, 3rd and long (at least I would think) would lead to lower PE.