Advanced Stats Review: GT Defense vs UNC
Final Score: Georgia Tech 21, North Carolina 17
Model Prediction: UNC by 21.9, UNC to cover: Incorrect
Projected EPA (Offense and Defense) Margin of Victory: GT by 12.8
GT Win Probability (Based on Success Rate, Yards Per Play, and EPA): 60%
Georgia Tech went up to Chapel Hill coming off of a frustrating loss against Miami and the loss of two quarterbacks. As a 21 point underdog and the victims of an early 17-0 deficit, Tech could have packed it in. And then Zach Gibson found his running backs to be his best weapon in the passing game, and the Georgia Tech defense turned back into the havoc-wreaking unit we saw in Mercedes-Benz Stadium against these same Tar Heels last year. Georgia Tech scored the game’s final 21 points, averting a potential go ahead UNC touchdown when Josh Downs dropped a pass in the end zone on fourth down and then running out the clock with some power running. It was an inspired win for the Jackets. Let’s dig more into the numbers, particularly to see how the defense shut down the mighty Tar Heels.
Advanced Stats Comparison
In our preview, we noted that North Carolina held the edge in 19 of 22 categories, but Georgia Tech managed to win 10 of the 23 categories we track in the game itself. This was not a win that was built on turnover luck or unsustainable explosive plays. Tech held solid EPA/play and success rate advantages, and the yards per play numbers would have been almost exactly even without UNC’s opening 80 yard scamper. The most impressive (and unexpected) numbers for GT here are in the passing game; Zach Gibson held decisive advantages over Drake Maye in EPA/drop back and yards per drop back. That wasn’t on my bingo card heading into Saturday. Georgia Tech won this game, and it was no fluke.
When North Carolina Had the Ball
Elijah Green took UNC’s first offensive snap for a way-too-easy 80 yard touchdown, as Georgia Tech’s linebackers fit poorly, and the deep safety took a terrible angle. North Carolina’s other first half touchdown drive came on the strength of two explosive passes to the tight end. Otherwise, the Georgia Tech defense clamped down, and the pressure from the front took over the game in the second half. After UNC had gone up 17-0, the next five possessions for the Tar Heels went: punt, punt, punt, interception, punt, which allowed the offense to begin methodically moving the ball and eventually grab the lead.
Running the ball was the most effective mode of offense for North Carolina on Saturday. The 80 yard run to open the game stuck out, but even without that play and without sack yardage, UNC still averaged 4.4 yards per carry. Georgia Tech stuffed almost no runs, and the Heels put up another exceptional opportunity rate; it didn’t end up overwhelming GT in this one because UNC largely went away from the run as the game progressed, but it does bode trouble for how things will go against u(sic)ga.
Back to this one, the defensive front mostly did their jobs against the run. Per PFF, D’Quan Douse graded at 92.1 on run plays. Sylvain Yondjouen was at 84.2, Makius Scott at 78.9, and Keion White graded at 74.6. The other Edge spot still struggles, as Kyle Kennard came in at 58.8, with Noah Collins even lower at 48.8. Kevin Harris got more snaps this week and was ok, but that rush end spot regularly gets washed on run plays. The weaker run defense came in the second and third levels, highlighted by a really poor Charlie Thomas performance at 53 and LaMiles Brooks down at 54, with a big penalty for taking an awful angle on the opening play. The final thing to note here is that Trenilyas Tatum still only received three snaps, and those came when Ace Eley briefly left with injury. The future at linebacker is very murky.
Here, we start to see how the defense came out on top. Finally, the solid pressure rates of recent weeks led to finishing some havoc plays. The defense recorded 12 TFLs overall, which is the most for GT since last year’s UNC game. This Carolina offensive line is a panacea for GT’s defense. In the pass rush department, Charlie Thomas led the way with an 81 grade, but Keion White was far and away the production leader. He had 6 pressures, 3 sacks, and one more TFL.
Elsewhere up front, Jason Moore played well on 16 snaps, grading out at 69.3. Douse put up 4 more pressures, while Moore and Scott had 2 each. This wasn’t a turnover fest for the defense, it was just solid disruption. Drake Maye’s yards per attempt went down from 7 to 5 when pressured. Encouragingly, GT’s defense posted a 31% pressure rate on just a 21% blitz rate. That helped set up the coverage well.
Georgia Tech’s secondary once again performed admirably, especially considering the opposing quarterback is fourth nationally in ESPN’s QBR metric, and his favorite receiver is a candidate for the Biletnikoff Award. Bottom line, Georgia Tech’s defense held Drake Maye to below average Completion Percentage Over Expectation, his worst raw completion percentage of the season, and a 16th percentile EPA/pass performance. When he did complete passes, his air yards per completion were about average, as was the average of 5.7 yards after the catch for the receivers. Georgia Tech used pressure to hurt the UNC passing game, and Maye largely couldn’t take advantage even when he got the throws off.
PFF didn’t grade the secondary as highly as I would have imagined, given the impressive top line numbers. La Miles Brooks was once again best at 70, Derrik Allen did a great filling in and came out at 67, Myles Sims was at 66, Zamari Walton was at 60, and KJ Wallace had the worst day of the regulars at 40. The secondary continues to play light years better than last year, and the emergence of the young contributors is exciting.
EPA calculates the expected number of points added (or lost in the case of a negative number) on a particular play based on the down and the location on they field.
As always, we’ll take a look at the most helpful and hurtful plays for GT.
Most Helpful Plays
- 3.95 EPA - LaMiles Brooks’s interception of Drake Maye on 2nd and 14 at the GT 23 while GT trailed by 3.
- 3.27 EPA - Zach Gibson’s 36 yard completion to Hassan Hall to get to the UNC 5 and set up GT’s first touchdown
- 3.00 EPA - The crucial drop by Josh Downs on 4th down from the GT 19 with 4 minutes left
- 2.99 EPA - Hassan Hall run for a touchdown on 3rd and goal from the UNC 6 to take the lead
Georgia Tech’s four most impactful plays included two failed UNC pass plays and two Hassan Hall highlights. The Downs drop was quite fortunate for GT, no question. But the defense did put UNC in a tough spot to have to throw a fourth down ball into the end zone trailing by four with four minutes left.
The Hall play is also representative of one of the most impressive number of the day for Tech: a 10.1 yards after catch average on completed passes. That is an enormous number and speaks to the concerted effort to get the ball to running backs in space to drive the passing offense.
Most Hurtful Plays
- -6.2 EPA - Elijah Green 80 yard run on UNC’s opening play
- -3.4 EPA - Gavin Steward missed 45 yard FG
- -3.09 EPA - Drake Maye pass to Josh Downs for 25 yards to the GT 18 on 3rd and 9 in the 4th quarter
- -3.08 EPA - Taisun Phommachanh’s interception on 3rd and 9 from the GT 26 early in the second quarter
Of course, UNC’s opening play was far and away the worst of the night for GT. Stewart’s missed field goal was disappointing but thankfully a rarity since he took over duties. The Phommachanh interception was the last pass he attempted all night; after that, the plan shifted considerably to only use Gibson in passing situations and Phommachanh in running situations.
Tracking Season Goals
*I set these goals for the 2022 season in some of my offseason preview work. We will be tracking them as we go this year.
GT Season Goals vs. UNC
|Metric||Season Goal||This Week||Season Long|
|Metric||Season Goal||This Week||Season Long|
|GT CPOE||>= 2%||-5.80%||-4.30%|
|Pressure Rate Allowed||<=26%||46%||34%|
|Run Rate on 2nd Down and Long||<=40%||63%||56%|
|Average Depth of Target||>=9||3.2||8.4|
|Defensive Passing EPA/play||<= 0.08||-0.1||-0.01|
|Defensive Havoc Rate||>=18%||25%||16%|
|Defensive Pressure Rate||>= 27%||31%||31%|
As has become custom, we see the offense falling short of our goals and the defense hitting them. The offense threw extremely short passes, primarily to running backs in this one, which ended up working quite well once Gibson started to get a rhythm and most of the snaps. It’s still confusing and concerning to see so many second and long runs. Why not replace those with more of the quick throws to running backs that were so successful? On defense, it’s great to see the passing EPA allowed, havoc rate, and pressure rate all come together to highlight a fantastic defensive performance.
- Leading the defensive effort, Keion White was able to put it all together on a big stage. The reigning ACC Defensive Lineman of the Week is now up to 38 pressures, 7.5 sacks, and a 75 pass rush grade for the year. That kind of presence is so impactful for GT’s front. He’s not along in the outstanding individual work though. LaMiles Brooks still sits at an 84 overall defensive grade for the year, and D’Quan Douse is right behind at 78. Those three have developed into GT’s most impactful defenders as the season has progressed.
- Hassan Hall, Dontae Smith, and Jamie Felix were unleashed in the passing game, and Zach Gibson put it where he needed to for them to get enormous yards after the catch. The biggest loss from not having Jhamyr Gibbs had been in the passing game; finally, GT’s stable of running backs found that kind of production to beat UNC. Felix looks like the back of the future, as well. He’s been great since starting to get touches against Virginia Tech.
- After going down two quarterbacks and facing a 17 point deficit, this team showed remarkable resolve. The defense clamped down and forced mistakes. The offense found space against a porous defense and exploited it. The team avoided any major missteps on both sides of the ball in the second half and got an excellent team win.
- I know that the tenor of the conversation after this one has been that Brent Key must get the job. Many players have taken to Twitter to voice that sentiment, and it’s grown markedly among the fanbase since Saturday. I would advise caution, patience, and continued analytical thinking. Yes, Key has engineered four wins. No, this team is not night and day better than it was when he took over. In our Binion Index power rating, the team sat at -7.3 after the UCF loss that got Collins fired. After Saturday’s win, that number is -6.6. It’s fun to win, and I encourage all the celebrating. But that doesn’t mean that Brent Key is the best option at head coach for the next era of Georgia Tech football. If J Batt decides that Jamey Chadwell is that best option and proceeds accordingly, I hope the fanbase can understand the bigger picture thinking that goes into that decision and support it.