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Stats O’War: Purdue Advanced Stats Preview

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The Frogs head to West Lafayette Saturday night for a rare Power 5 non-conference road game.

Hello friends, and welcome to the meat of the football season. We’ve gotten Week One out of our system and even gotten a few great games under our belts: Hawaii-Arizona, LSU-Texas, Auburn-Oregon, Nebraska-Colorado, to name a few. This week, week three, the college football season grows up in a sense; we make the turn from fun preseason excitement to in-season drama, from quenching our thirst for college football with Thursday night FCS games and 11 pm Hawaii kick-offs to match-ups with playoff implications, from expectations to reality, from faith to sight.

TCU has been an unsatisfying kind of off-the-radar during the first two weeks of the season, following their standard FCS opener with an uncharacteristic Week 2 bye. The start of the season for TCU fans has been in ways a “gotcha” moment, wherein we all exercised our college football offseason demons in Week 2, then were forced to sit on our hands for two whole weeks while the rest of the country marched on with the college football schedule.
That all ends this week, though, as TCU faces a real, live football team in the Purdue Boilermakers. Purdue is in the early stages of a potential Renaissance, winning more games in Jeff Brohm’s first two seasons (13) than they did in all of Darrell Hazel’s 4 year tenure (9) and already reaching Danny Hope’s career high for wins at Purdue (7 games).

Purdue comes into this matchup on the back of a disappointed season opener, where a dismal rushing game hamstrung their ability to put a game away and their defense allowed 27 second half points in a loss to Nevada. The Boilermakers righted the ship somewhat against Vanderbilt, but key injuries to defensive anchors and a concussion question mark at QB have Purdue in a precarious position going forward.

TCU and Purdue have been historical bedfellows, in terms of team quality. Looking at historical program trends (thanks to collegefootballdata.com’s slick visualization tools), Purdue edged out TCU in SP+ for virtually the entire 20th century, only to see a recent steady shift in favor of TCU thanks to the hiring of one Gary Patterson.

Some struggles on offense and the aforementioned Brohm Renaissance have Purdue and TCU as basically equals last year, but since about 2008, TCU has far and away been the better program.

TCU Horned Frogs (30th in SP+, 79th off, 16th def)
at Purdue Boilermakers (57th, 28th, 95th)

SP+ Prediction: TCU 36, Purdue 30 (62%), over 51.5

We see a theme familiar to the Big 12 Frogs: TCU, a defense-first and offense-lagging team, faces a conference slate full of teams with Purdue’s makeup: fast, offense-heavy, defending only enough to keep the offense ahead. When comparing rankings between two teams, we can of course be informed by comparing the ordinal rankings, but we can clarify by considering the cardinality - the magnitude of the distance between the two teams.

SP+ has the teams a net 7.6 points separated: TCU is +11.0 overall, where Purdue is +3.4. The projected six point spread accounts for home field advantage in favor of Purdue. On offense, the Boilermakers rank +42.4, comparable to teams like Missouri, Notre Dame, Wisconsin, and not too far ahead of SMU. TCU’s defense is a +20, similar to Virginia, Boise State, Washington, UCF, and Oregon.

It’s hard to do too much with the data after only two weeks - you’ll note, the SP+ rankings are still projection-heavy.

In the meantime, let’s look at the stats we do have a try to discern where Purdue excels and how TCU might stop them.

Purdue Offense vs TCU Defense:

I won’t focus as much on TCU’s numbers - these are not opponent adjusted, and TCU played an FCS team, whereas Purdue has two FBS matchups. What we see from Purdue, though, is a lethal passing attack married to a less-than-stellar rush attack. Purdue is successful on almost 50% of plays, and 54% of pass plays, for an average of 7.194- that’s certainly inflated by a couple of long Rondale Moore plays, but is entirely driven by the pass. The Boilermakers average almost 7 more yards per play on passes than rushes. Their explosive play rate is 19.4%, meaning that 1 in 5 of their offensive plays goes for a big chunk of yards.

Explosiveness is the name of the game for Purdue; of their 10 touchdowns this season, 5 came on plays of at more than 30 yards. 10 of their 11 scoring drives this season involved a play of at least 20 yards, and the eleventh drive featured plays of 19 and 15. Last year, Purdue was 10th in IsoPPP, at 1.31. For reference, TCU’s offense last year was 109th (1.03) and the Frog ranked 57th, allowing 1.14.

The Purdue offense is multiple and it is deep. Stoping the Boilermakers will be conceptually simple, though - TCU has to limit big plays, and they have to turn the water off on the passing game. Fortunately, the Frogs have experience shutting down high-powered offenses. In the Oklahoma State game last year (24th in explosiveness) to 24 points, and only 5 plays over 20 yards (two of which came on the same touchdown drive). Last year’s Oklahoma State game looked a lot like this:

If TCU wins on Saturday, I imagine it’ll be in no small part a play-by-play looking like the above.

TCU Offense vs Purdue Defense

Switching to the other side of the ball, we come back to a touchy issue: the TCU offense. I can’t say anything here I haven’t already said on Twitter or in my column last week, so I’ll focus on Purdue’s defense.

The good news: Purdue’s defense is bad! They’ve given up double digit second half totals in both games this season, and given up 24 and 31 points to not-great offenses. The defense has played well, on the averages, but when you factor in some injuries, this unit is going through some struggles. Purdue returns a whole lot of their defense from last year, but the quality is still to be determined. Especially worrisome for Purdue is the 34 points they gave up to a Nevada team who only scored 7 versus Oregon. With injuries and a tough offensive pace (no run game means quick drives), this defense will be especially susceptible to getting worn down. Look at their second half numbers:

Passing success rate allowed goes all the way up to 43, a near five percentage point increase. Over the course of the game, TCU will have opportunities to exploit a thin defense.

Prediction

I like the SP+ numbers on this game. TCU is a close road dog, and I like not being favored going into a road game. This all depends on quarterback play, for both sides, and I get the sense this game could just as easily be a 20-13 slog as it could a 55-54 old west shootout. If you’re TCU, you’re hoping for the former.

I expect a one-score game, late, and a slight TCU edge. I’ll take SP+ and level shift it down a few scores, because I don’t trust TCU’s offense: TCU 30, Purdue 28

Other Games I’m Watching:

A little bit of a light slate this week; I’ll be headed to Fayetteville to watch Arkansas and Colorado State (family reasons), but I’ll be keeping my eye on Mississippi State-Kansas State, and on Texas Tech-Arizona. Both are good measuring sticks for uncertain Big 12 teams.