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How Good Was UCF's Defense in 2017?

Summer Study Hall

Shaquem Griffin showed NFL scouts and coaches Thursday that he can do more than sack quarterbacks.

))990)))))
Photo: Derek Warden)
Shaquem Griffin showed NFL scouts and coaches Thursday that he can do more than sack quarterbacks. ))990))))) Photo: Derek Warden)

With all of the hoopla surrounding UCF's mind-blowing offense in 2017, it's easy to forget about the defense. Defense is underappreciated, and in the era of the spread, it's even more underappreciated than ever.

Bend-but-don't-break philosophies are becoming a necessity with the advent of offenses that toss their defenses out on the field for extended periods and multiple possessions. Teams are giving up lots of yards and points, all in the name of getting the ball back for the offense to do its thing. So how do we measure success?

I presented a different way of evaluating UCF's offensive success - by possession - in a previous article. Now we're going to take a look at the defense using similar metrics.

2017's Defense

UCF's defense had the unenviable task of playing alongside the nation's most prolific scoring offense, which also ranked 105th in FBS in time of possession. They knew they were going to be on the field a lot, and likely give up a ton of yards and points.

That mostly bore out: UCF was 93rd in FBS in total defense (427.9 yards per game allowed), although they were 52nd in scoring defense (25.3 points per game allowed - not all that bad).

More significantly, they had to make up for that yardage total by turning the ball over, which they did at a tremendous clip: UCF forced 32 turnovers last year, second only to Wyoming in FBS.

But we need to look deeper than that to see how good this defense really was, and that requires looking at possessions.

Once again, we turn to the drive charts and box scores:

  • TD – Touchdown
  • FG – Made field goal
  • FGA – Field goal attempted and missed
  • PUNT – Duh.
  • FUM – Lost fumble
  • INT – Interception
  • DOWNS – Turnover on downs
  • HALF – Possession ended with the end of a half

Let's also define a turnover as any of the following results: fumble, interception, turnover on downs, safety, blocked punt or blocked field goal.

Here's UCF's defensive performance in 2017 by possession:

GAME TD FG FG Miss Punt Half Turnovers Def/ST TD TOTAL Defensive Points Allowed
FIU 2 1 7 5 15 17
Maryland 1 1 1 7 1 3 14 10
Memphis 2 4 6 12 13
Cincinnati 3 1 4 1 9 23
ECU 3 8 2 2 15 21
Navy 3 3 1 5 12 21
Austin Peay 3 3 2 3 2 11 21
SMU 3 1 1 7 1 3 1 16 17
UConn 3 1 5 1 5 15 24
Temple 2 2 1 3 1 6 15 19
USF 6 1 6 3 16 42
Memphis 7 2 2 3 1 2 17 55
Auburn 3 2 1 5 3 14 27
TOTAL 41 11 7 65 10 47 3 181 310

Again, a few notes:

  • Defensive points do not include touchdowns that the opponent scored on defense or special teams since that's not the defense's fault as they weren't even on the field.
  • HALF possessions are considered non-possessions in the upcoming calculations because it's impossible to determine intent in those possessions.
  • Turnovers = fumbles, interceptions, turnovers on downs, safeties, blocked punts or blocked field goals.

Now let's answer some questions.

What I Found Out

How often did UCF's defense stop the opponent?

Stop Rate

The defense's job is simple: Stop the opponent's offense from scoring.

We can define stops as punts + turnovers as defined above. Missed field goals should not count as stops since it really wasn't up to the defense. They allowed the opposing offense to get into field goal range, and it's the kicker's fault, not the defense, that the opponent got no points.

So let's add the number of punts forced and turnovers forced and divide by total defensive possessions:

(65 punts + 47 turnovers) / 181 total possessions = 61.9% Stop Rate

Takeaway Rate

Turnovers are how the defense gains more advantageous field position for the offense than by forcing a punt. So let's find out how often that happened:

47 turnovers / 181 possessions = 26.0% Takeaway Rate

How often did UCF's defense give the opponent a chance to score?

Opponent's Scoring Opportunity Rate

Whether or not an opponent scores is sometimes not up to them, like if a kicker misses. But the key to answering one of the questions we ask above is finding out how often the defense allows the offense a chance to score. So we can measure that by adding the following:

(41 TDs allowed + 11 FGs allowed + 7 missed FGs) / 181 possessions = 32.6% Opponents' Scoring Opportunity Rate

Points Per Possession Allowed

This might also help us: How many points did UCF's allow per time it was on the field?

310 defensive points allowed* / 181 possessions = 1.71 points per possession

*Defensive points allowed = Opponents' offensive TDs only + ensuing extra points + field goals. No safeties, defensive TDs, special teams TDs or their ensuing extra points are counted.

What Does It All Mean?

Just like we did before, let's go grab that five seasons' worth of context so we can make some comparisons:

Year W/L Def. Poss. TD FG Punts Turnovers Def/ST TDs Half Def Pts.
2017 13-0 181 41 11/18 65 47 3 10 310
2016 6-7 203 38 14/22 89 44 2 10 306
2015 0-12 167 56 17/18 58 19 2 16 434
2014 9-4 177 27 16/20 77 43 2 10 242
2013 12-1 155 34 8/12 66 37 2 6 263

Now we can compare the breakdowns of the advanced stats we had above:

Year W/L Stop Rate Takeaway Rate Opp. Scoring Rate Opp. TD Rate Pts./Poss. Allowed
2017 13-0 61.9% 26.0% 32.6% 22.7% 1.71
2016 6-7 65.5% 21.7% 29.6% 18.7% 1.51
2015 0-12 46.1% 11.4% 44.3% 33.5% 2.60
2014 9-4 67.8% 24.3% 26.6% 15.3% 1.37
2013 12-1 66.5% 23.9% 29.7% 21.9% 1.70

Conclusions (?)

Doing this defensive analysis was a bit less conclusive than the offensive analysis. The numbers seem a bit less conclusive, but nonetheless, here's what I drew out of them:

  • 2015 was AWFUL.
  • 2017's defense gave up a lot. That team gave up the highest opponents' scoring rate, opponents' TD rate and points allowed per possession than any other team in this 5-year span with the exception of the 2015 catastrophe.
  • But they also took the ball away a lot - the highest turnover rate of the five-year span.
  • 2014's defense was very good. But it wasn't head-and-shoulders above the rest, with the exception of one thing: They forced a LOT of field goals. Look at the TD Rate.
  • 2016's defense was actually pretty good.

Again, there's still plenty more that has to be done here to draw definitive conclusions. However, given the limited sample size, I can hypothesize a few benchmarks that UCF's defense might need to achieve in order to have a successful season:

  • Stop Rate > ~60%
  • Takeaway Rate > ~20%
  • Opponents' Scoring Rate < ~30%
  • Opponents' TD Rate < ~25%
  • Opponents' Points per Possession < ~1.75

I'd be interested in finding out these numbers across The American last year, and across more conferences, if I could. That requires time.

I'll also be synthesizing these numbers with the offensive ones and looking at some other numbers as well. But rest assured that we'll be keeping track of these kinds of numbers through the 2018 football season.