While trying to predict the effect of the losses of Javon Ringer and Brian Hoyer to MSU, I read all kinds of stats like "Javon Ringer only averages 4.2 yards per carry" as though it's a bad thing. Bad? Good? From the face of it, who knows? [Not very good, it turns out]. So I started toying with the idea of adjusted stats. One of my favorite stat creations of the sabermetricians is the concept of the "+", the "plus", where stats are adjusted based on league factors (and, in the case of baseball, park and team factors). So I set out to create some new stats that used the concept of the "plus". At the same time I wanted to fix what I see are two shortcomings in college football stats.
First of all, "sacks" and their resulting lost yardage are counted as rushing attempts, when they really should be included as passing attempts.
Secondly, there isn't really a way to penalize a team for an interception save an arbitrary weighting of interceptions per pass attempt as a component of the Passer Rating stat. So I decided to subtract the interception return yardage from the normal passing yardage as a penalty to the quarterback for letting his throw get picked off in the first place. For team stats, this also affects the team for allowing the defensive player to return the ball.
So the two new stats I just made up just now are:
NYPPA [Net Yardage per Passing Attempt] where NYPPA = (pass yards - |sack yards| - |interception return yards|) / (attempts + number of sacks). I also calculated Adjusted NYPPA, NYPPA+, where NYPPA+ = (team or player NYPPA / FBS overall NYPPA) * 100. NYPPA+ of 100 equals exactly average.
NYPRA [Net Yardage per Rushing Attempt] where NYPRA = (rushing yards + sack yards) / (attempts - number of sacks). so NYPRA+ = (team or player NYPRA / FBS overall NYPRA) * 100
I did the initial calculations using team passing stats from cfbstats.com. When I sorted by NYPPA+ I noticed that generally the "best" teams (Florida, Oklahoma, Texas) had the highest NYPPA+. To investigate further, I then ran a correlation between my three new made-up stats and win percentage (win percentage stats coming from stassen.com).
Coefficient of Correlation between NYPPA+ and win percentage is 0.65. Between NYPRA+ and win percentage is only 0.36. Thus, the better at passing a team is, the more likely they have a higher win percentage.
So. What does this mean for MSU, losing Brian Hoyer? Hoyer's NYPPA+ in 2008 was a below-average 98.32. Hoyer regressed slightly during his last two years, going from NYPPA+ of 102.28 in 2007 to 98.32 in 2008, both representing mediocre performances. And Ringer? Ringer posted a NYPRA+ of 86.94 in 2008. Some of this comes from the playcalling, but the truth remains that Javon Ringer, while a workhorse back, was not by any means one of the top running backs in the country.
I for one am optimistic that Michigan State's offense will not be any worse off in 2009, despite the loss of Ringer and Hoyer. Fact is, Hoyer wasn't very good in 2009, but he wasn't terrible either. Michigan State was winning games, so there was no impetus for Dantonio to make a switch at quarterback. Kirk Cousins [small sample size alert!] had an NYPPA+ of 112.77 in 2008. It looks like the passing offense should be improved overall in 2009.