How much has Clayton Thorson really developed?

Clayton Thorson stood at his own 25 at Kinnick Stadium last Saturday, facing an Iowa team that had just reeled off 17 unanswered points and a defense that had just forced a Justin Jackson fumble. The Hawkeye faithful were at full volume. Last year’s edition of Clayton Thorson might have shriveled up into a ball. Or, who knows? Mick McCall might have decided to repeatedly call Jackson’s number in an effort to hide his young quarterback against an aggressive defense. Regardless, it wouldn’t have been pretty.

But that was last year’s Clayton Thorson. Perhaps more importantly, that was last year’s Mick McCall. And while neither have been perfect — far from it — the confidence the latter has gained in the former, and rightfully so, has been an important development, and it showed in the most crucial moments of Northwestern’s most crucial game to date. Thorson completed eight of his next nine throws, two of which were touchdowns, as Northwestern reached the end zone three times in as many drives to put the hosts away. It was the best stretch of his career in what Pat Fitzgerald called “the best game of his career.”

But to say that Thorson has improved mightily based on his best string of plays would be irresponsible. That Thorson has improved is absolutely clear. His best in 2015 was never quite as good as he was against Iowa a week-and-a-half ago, and his lows of this year aren’t as bad as his lows last season, especially when considering how awful he was even in games Northwestern won, the Duke game being a prime example.

To accurately assess Thorson’s development, several aspects have to be looked at. The one that most fans will point to first to support Thorson’s development is his major improvements in the passing game.

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The proof of improvement is right here in these relatively basic stats. Thorson has nearly doubled his yards per game by raising his yards per attempt by over a yard.

The stats also include some improvements that we expected when we posed the question of “How much will Clayton Thorson improve?” in the offseason. He’s cut down on his interception rate (down from approximately one per every 33 throws to approximately one every 42 throws), thrown more touchdowns, elevated his completion percentage and simply been a better, more efficient passer.

There are, of course, several other factors at play. One of the stats from the graph above is sacks per attempt, where Thorson’s number has actually gotten worse. He’s being sacked once every 10.6 passing attempts this year, a significantly worse mark than his one sack per every 13.4 attempts last year. Whether that’s due to the offensive line play, which has simply been horrendous at times; the lack of a consistent running game (the two are strongly related); a need to throw deep more often when trailing or simply Thorson’s propensity to hold on to the ball too long is up for debate, but the answer is probably some sort of balance between the four. There are times when Thorson needs to unload more quickly, as he did versus the Hawkeyes.

“I think he made some really good decisions from the standpoint of hitting some wide open fans in the stands,” Fitzgerald said. “The week before, he took a couple of ill-advised sacks and we had some wide open at Ryan Field up in the first few rows that he should have completed the balls to... It’s not always his completion percentage that matters.”

But completion percentage does matter a significant amount, even if Fitzgerald is spot on about throwing the ball away instead of taking drive-killing sacks, and that’s one area in which Thorson hasn’t made quite the progress that could really take his game to the next level. He still misses too many relatively simple throws, and is seldom accurate when forced to squeeze the ball into tight coverage. The end zone interception against Nebraska comes to mind as a key mistake. Thorson is more accurate this year, and he’s been asked to make more downfield throws than he was last year, but his accuracy still leaves something to be desired.

What’s interesting about that Thorson statistic, though, is that his mid-50s completion percentage comes from exactly zero individual games with a completion percentage in the 50s. He has three games (WMU, Neb. and Iowa) in which he’s completed at least 60 percent of his passes and two games (ll. St., Duke) in which he’s completed under half of his throws.

The biggest difference in those two categories is how effectively Northwestern ran the ball. Against WMU and Iowa, Jackson found ample space and racked up about 300 yards combined. Even against Nebraska, he averaged just a hair under four yards per carry. But against Illinois St. and Duke, the two worst games of Thorson’s year, completion-wise, Jackson ran for a measly 3.4 yards per carry. Thorson struggled accordingly.

That can be taken as a positive — when the running game is effective, Thorson can be very efficient — or a negative: Thorson is yet to reach the point where he can put an otherwise-struggling offense on his shoulders and carry it to victory. But unlike last year, where McCall stuck with an “If it’s not broke, don’t fix it” strategy regarding running the ball, McCall has been able to mix up his playcalling when Jackson is finding success. The results have been mostly positive when he has that ability: three touchdowns in eight possessions versus Western Michigan and 38 points against Iowa. When the running game works, Thorson has the ability to provide balance, which he didn’t last year.

Another category to look at when assessing Thorson’s development is the personnel surrounding him. The offensive line has certainly regressed, but his wide receivers have unexpectedly improved. Austin Carr is the conference’s best receiver, statistically, and Flynn Nagel, Macan Wilson and others have performed well, too. At the very least, the group is not dropping nearly as many passes as it did last year and has been far better after the catch. It’s hard to determine exactly how much of an impact “better wide receivers” has on a quarterback’s development, but it certainly can’t hurt.

Still, when advanced stats come into play, Northwestern’s offense as a whole has not progressed as much as Thorson has, a curious outcome given that last year it was Thorson and his pass catchers that held the offense back significantly. The Wildcats are better in offensive S&P+ (83rd compared with 111th) and passing offense (91st compared with 112th), but those numbers certainly don’t hark back to the more successful days of the McCall system, and part of that is because the explosive plays are still lacking. While there are plenty of individual cases to choose from — three long touchdowns versus Duke, Jackson’s runs against Western Michigan and Iowa — Northwestern’s Isolated Points Per Play Plus, a measure that accounts for how many of your successful plays (50 percent of necessary yardage on first down, 70 percent on second down, and 100 percent on third and fourth down) are really successful rather than just a little successful, remains in the doldrums of FBS rankings. To understand this metric, here’s an excerpt from Bill Connelly, the creator himself:

PPP is basically a combination of yards per play and the acknowledgement that not every yard line is created equally. I assign an equivalent point value to every yard line, then assign a point value to every play. (You can see PPP in use in Football Study Hall's weekly advanced box scores.)

Essentially, when Northwestern does produce successful plays, it rarely produces big ones (IsoPP throws out all “unsuccessful plays”). So a five yard gain on first down, while efficient, is not explosive. In these terms, you have to be efficient to have a chance to be explosive, but Northwestern rarely is. The Wildcats placed 109th last year and are 105th this year. While Thorson has been significantly better, Northwestern is still just 97th in the nation in yards per attempt at 6.6. That’s not going to make for very explosive plays, and it’s going to make for far too many plays that go nowhere, an issue that comes from his inaccuracy.

So how much has Thorson really developed? Well, he can do significantly more when the run offense is thriving and he has been noticeably better overall. But issues with accuracy still plague him, and when Jackson isn’t finding space, he’s yet to take the step up to being a guy who can win games by himself. Perhaps that’s not to be expected yet from a player who was on a leash last year and has been in some difficult situations in 2016. Has he come as far as Northwestern needs him to in order to have a good offense and contend in the Big Ten West? The stats and eye test say no.

Still, there have been substantial signs of improvement from Thorson in his decision-making, his ability to make plays to provide offensive balance (completely non-existent last year) and his willingness to go downfield with the ball.

It’s a process that shows he still has a long way to go, but also one that shows that he is finally beginning to show the promise he came in with as a four-star recruit. And that alone is encouraging, if imperfectly so, for the continuing development of the sophomore signal-caller. The remainder of the season will give us plenty of time to determine if Iowa was truly a step in the right direction or yet another example of how frustrating developing a consistent quarterback can be.