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Advanced analytics say Northwestern is good practice for Ohio State’s offense

With Wisconsin on deck, a Friday night game against Northwestern’s solid defense is great for development

NCAA Football: Big Ten Conference-Football Championship-Northwestern vs Ohio State Thomas J. Russo-USA TODAY Sports

It might not have seemed like it earlier in the season, but Michigan State and now Northwestern were excellent warm up games for Wisconsin. Neither the Spartans nor the Wildcats have an offense, but their defenses are elite.

For example, the chart below shows offensive vs. defensive expected points added (EPA) per play (you want to be down and to the right):

As you can see, Northwestern has one of the very worst offenses in the entire country. But they’re also in the tier of elite defenses, similar to Penn State, Clemson, Georgia, and Alabama.

So this is a great tune-up game before the Buckeyes have to face a much more balanced Wisconsin team — that as you can see above, is not far behind the Buckeyes offensively, but has the country’s best defensive in EPA per play.

Alright, so how can Ohio State score on the Wildcats?

OSU offense vs. NW defense

Stat Ohio State offense Northwestern defense
Stat Ohio State offense Northwestern defense
Avg EPA 94% 91%
EPA SR 92% 80%
Rushing EPA 88% 79%
Rushing EPA SR 84% 80%
Short Rush EPA 59% 22%
Passing EPA 88% 88%
Passing EPA SR 95% 69%
RZ EPA 93% 95%
RZ EPA SR 91% 91%
Std Down EPA 83% 47%
Pass Down EPA 58% 78%
  • The EPA stats in the table above are expressed as percentiles in a normal distribution (I took each team’s EPA stat in terms of the standard deviations from the mean, then converted those z scores to percentiles). This is because EPA takes a little bit of context to be meaningful, but percentile ratings are easy enough to understand. If anyone would rather see regular EPA ratings, please let me know!
  • It’s easy enough to see that this is strength-on-strength. Ohio State and Northwestern have similar overall EPA per play percentiles (94% vs. 91%).
  • The biggest takeaway for me is that the Buckeyes offense will live and die based on their performance on standard downs. Ohio State is in the top 17 percent in standard downs EPA, while Northwestern’s defense is actually slightly below average. But Northwestern is much better (78%) on passing downs, while Ohio State is only slightly above average (58%) in EPA per passing down. This reminds me of Ohio State’s efficiency vs. explosiveness split:
  • The above chart shows offensive EPA success rate on the x axis and average EPA per successful plays on the y axis. This gives a sense for efficiency on the x axis, and explosiveness on the y. Ohio State is among the most efficient teams in the country, but they actually aren’t very explosive given their efficiency. The Buckeyes clearly aren’t as reliant on efficiency as someone like Georgia or Wisconsin, but the point still stands that there is a chance that the Buckeyes offense could be suffer if a defense is able to lower their efficiency because they might not be able to compensate with big chunk plays. That said, Ohio State has shown some ability in terms of explosiveness — Ohio State is 11th in overall explosive play rate — but those explosive plays aren’t always the take-it-to-the-end-zone kind. Those big plays can help bail you out even if you see a dip in efficiency overall because they can instantly put you in scoring position.
  • The other major thing to note is the difference between Northwestern’s average passing EPA (88%) and their passing EPA success rate (69%). This suggests that Northwestern is much better at preventing explosive pass plays than they are at stopping efficient passes overall. So I’d look for Fields and company to continue their efficiency-based passing game, with a lot of underneath and mid-range passing that might not necessarily have a ton of yards after catch.
  • Despite Northwestern’s really great defense, they don’t get a ton of pressure, ranking 86th in overall havoc rate. That is good considering Ohio State may be down two offensive tackles with Alabi out and Thayer Munford as a game time decision (my guess is they would like to sit him with Wisconsin looming).
  • Finally, Northwestern is elite at slowing you down in the red zone, ranking in the top five percent in red zone EPA and 11th overall in scoring opportunity touchdown rate (allowing just 36 percent of scoring opportunities to end with a touchdown). So the Buckeyes will really need to work on not settling for field goals.

What do we need to know about the Wildcats offense?

NW offense vs. OSU defense

Stat Northwestern offense Ohio State defense
Stat Northwestern offense Ohio State defense
Avg EPA 11% 95%
EPA SR 35% 97%
Rushing EPA 42% 71%
Rushing EPA SR 56% 91%
Short Rush EPA 24% 37%
Passing EPA 6% 95%
Passing EPA SR 21% 97%
RZ EPA 16% 90%
RZ EPA SR 40% 96%
Std Down EPA 9% 45%
Pass Down EPA 20% 88%
  • Northwestern’s offense is almost historically bad. Despite former five-star quarterback and Clemson transfer Hunter Johnson entering the program, the Wildcats offense is among the worst in the country. It is in the bottom 11 percent in EPA per play.
  • The Wildcats are dead-last in the FBS in havoc rate allowed, with a havoc play on 26 percent of downs. They allow a run stuff on 20.8 percent of rush attempts.
  • I don’t think we need to get too much in the weeds on this side of the ball. It’s enough to know that, as Banner Society’s Richard Johnson pointed out on the last PAPN, Northwestern has maybe the largest difference ever in terms of offensive and defensive SP+.