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Stats of the Week - Bye Week #2

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Some interesting stats for thought during NU's second bye week of the 2013 season.

Jeff Hanisch-USA TODAY Sports

In Position to Win

Northwestern, of course, dropped another heartbreaker this past week, making it three consecutive losses by one score or less. I'll dig a bit deeper into this by evaluating the statement that Fitzgerald has put NU in a better position to win games than his predecessors.

First off, let's review the respective winning rates for NU's last three head coaches (the listed date restrictions are used throughout this article):

Coach Date Range Games W-L W Rate
Gary Barnett 1995 and later 48 27-27 0.563
Randy Walker All 83 37-46 0.446
Pat Fitzgerald through 11/02/13 98 54-44 0.551

Recent NU Coach Win Rates

Now, let's look more closely by evaluating the coaches based on the score of their games after three quarters (in other words, is their team in a position to win?). The three numbers presented are: % games leading after 3 quarters / % games tied or leading after 3 quarters / % games leading, tied, or within 7 points after 3 quarters.

Coach leading tied or leading tied, leading, or within 7
Gary Barnett 45.8% 60.4% 87.5%
Randy Walker 34.9% 43.4% 53.0%
Pat Fitzgerald 59.2% 65.3% 76.5%

% of games with given margin after three quarters

Barnett (1995 and later) did a great job staying within striking distance with one quarter to play, but one can see that Fitz is doing a relatively stellar job at putting NU in a position to win - the 'Cats have led going into the fourth quarter in almost 60% of the games that he's coached, and he has put NU within striking distance in over three quarters of games. And while Walker's teams were known to pull off some big comebacks, the fact that his teams led going into the fourth in just over a third of games put the Wildcats behind the 8-ball more often than not.

Some notes on Fitz's games when NU was not within striking distance going into the fourth: 11 of those 23 occasions were during his first two seasons (2006-07), and NU has only averaged 2 such games per season thereafter. Also 4 of those games occurred during the Persa achilles injury timeframe.

Hopefully I'll have a chance to dig a bit deeper into this topic later, but now on to some in-game stats that directly affect the outcome of the game.

Turnovers and Sacks

It's common football knowledge that the turnover margin often predicts the winner of the game, now let's explore that under Fitz plus another predictive statistic: sacks. But first, let's just look at NU's win rates under Fitzgerald at various turnover margins:

Turnover Margin % of Fitz's Games W-L W Rate
Positive 44.9% 29-15 0.659
0 19.4% 13-6 0.684
Negative 35.7% 12-23 0.343

Turnover Margin & Win Rates under Fitz

Takeaways: Fitz has done a good job of getting NU to a turnover margin greater than or equal to zero (64.3% of the time), and, not surprisingly, NU quite often wins those games (exactly two thirds of them). But, that means NU still loses a third of those (not an insignificant percentage), and conversely, NU has won about a third of the games in which it lost the turnover battle (which NU has done a little over a third of the time under Fitzgerald).

Let's look at something which is a little more telling, sack margin (NU sacks minus opponent sacks):

Sack Margin % of Fitz's Games W-L W Rate
Positive 35.7% 29-6 0.829
0 16.3% 10-6 0.625
Negative 48.0% 15-32 0.319

Sack Margin & Win Rates under Fitz

Takeaways: sack margin seems to have a bigger impact than turnover margin in determining the game's winner, with the 'Cats coming out ahead almost 83% of the time when out-sacking its opponent. Unfortunately, Fitz's teams haven't done that consistently, ending up with a sack margin greater than or equal to zero just 52% of the time.

Now, let's add the two above together to come up with an even more telling stat: turnover plus sack margin:

TO + Sack Margin % of Fitz's games W-L W Rate
Positive 39.8% 33-6 0.846
0 10.2% 8-2 0.800
Negative 50.0% 13-36 0.265

Turnover + Sack Margin & Win Rates under Fitz

Takeaways: Northwestern wins almost 84% of the games in which it has a turnover plus sack margin of zero or greater. That is very good, but that only happens in 50% of Fitz's games. In the other half of games in which that combined margin is negative, NU only wins about a quarter of the time.

Finally, let's look at what should be one of the easiest things to fix in that equation: sacks allowed. The ability to get sacks and create turnovers largely depends on what the other team is doing (if they run the ball a large portion of the time those are difficult to generate). For these stats, I'll bring back in comparisons to the previous two NU head coaches.

NU Coach % of games W-L W Rate
Gary Barnett 68.9% 21-12 0.636
Randy Walker 67.5% 31-25 0.554
Pat Fitzgerald 58.2% 44-13 0.772
Games allowing 2 or fewer sacks

NU Coach % of games W-L W Rate
Gary Barnett 31.3% 6-9 0.400
Randy Walker 32.5% 6-21 0.222
Pat Fitzgerald 41.8% 10-31 0.244
Games allowing 3 or more sacks

Takeaway: the stats here speak for themselves: when NU allows two or fewer sacks in a game, it wins most of the time, particularly under Fitz (when that rate is above three quarters of the time), meanwhile when NU allows more than that, it loses about three quarters of the time.

I'll leave you with one very telling stat: Under Fitz, NU is 13-0 when allowing no sacks in a game. That happened quite often during his most successful seasons: four times in 2008 (9 win season), and four times last year in 2012 (10 win season).