ASU scored fewer points this year than it had in any other year since Todd Graham became head coach, averaging only 33.8 points per game. The struggles on offense brought a lot of criticism for Offensive Coordinator Mike Norvell (now the head coach at Memphis), one of the most common being that he too often abandoned the run game. So, I wanted to take a look at the offense and try to figure out how balanced it was, and I wanted to do it in a way that is a little bit different.
If you watch a lot of football on TV you’ve seen that when analysts talk about run/pass balance, they usually reference the ratio of a team’s run plays to pass plays. ASU ran the ball 51% of the time, and threw on 49% of offensive plays. Pretty balanced, right? Is this the best way to determine if a team’s run/pass mix is the optimal one, though? I don’t think so.
Game theory is the science of strategy, and tries to determine, mathematically, the actions that should be taken in order to secure the best outcome. So we’re going to use game theory to determine if ASU’s run/pass mix was optimal, or something close to it. I can’t claim this method as my own, however. The first time I saw this analysis done was on Chris Brown’s Smart Football website. You can find his article on run/pass balance here.
Here’s how it works: The goal on offense is to gain as many yards as possible on any given play, especially first and second down. The way to do this is to call a mix of run and pass plays that results in the highest average yards per play. Mathematically, the yards per play is highest at the point at which yards per rush equals yards per pass play (we don’t want to use yards per pass attempt, since this leaves out sacks). This is the case because yards per rush (or yards per pass) goes down as the number of rushes (passes) increases, because defenses adjust to what a team does well.
Imagine a team that has a great run game – two amazing running backs and a great run-blocking offensive line. At some point, opposing teams will start to adjust to try to stop the run – probably by stacking the box, and their yards per rush will start to decrease. How do they respond? By throwing the ball, usually using play-action, and probably with some significant success. Their yards per pass play will therefore probably be pretty high. How often should they pass in order to maximize their yards per play? As stated above, they should pass enough so that their yards per pass play equals their yards per rush. So, if this team with the great run game averages 6 yards per rush, but 10 yards per pass play (because the defenses they face focus so much on stopping the run), they’re actually leaving a lot of yards on the table by not passing more often.
Before we look at ASU’s numbers, I want to add a note. Although yards per play is maximized at the point where yards per rush equals yards per pass play, this may not actually be the optimal mix, since pass plays carry more risk than run plays (passes result in more turnovers than runs). It’s probably a good idea, then, to require slightly more yards per pass play than yards per rush. As Chris Brown noted in his article, good offensive teams have a passing premium of about a yard, so that’s what we’ll go with here.
ASU in 2015
Now we’re ready to look at ASU’s numbers. Here are their 2015 rushing and passing statistics:
Since rush attempts and rush yards include sacks and sack yards, respectively, we need to move them to the passing category. If we do that, and then calculate the yards per rush and yards per pass play, we get the following:
If we do the math, we see that ASU’s yards per pass play is .75 yards/play higher than their yards per rush. Since we’re making the assumption that the optimal mix of run/pass is where yards per pass play is 1 yard higher than yards per rush, ASU is really close to being optimally balanced. You could make the argument that ASU should have run the ball a little bit more, but you’d really be nitpicking.
So, despite all the complaints about Mike Norvell frequently abandoning the run game, the numbers paint a different picture. This is not to say that ASU always ran the ball as much as they should have – there certainly were situations where you could argue that they threw the ball when they should have run – but overall, they were quite close to being optimally balanced.