A quantitative analysis of the FSU defense's improvement under Charles Kelly

Before the 2015 season began, I had the opportunity to speak with several Florida State football coaches and players about just how the defense would improve from a rather disappointing previous campaign. Their responses included a number of similar sentiments. Responsibility. Accountability. Stay home. Do your job.

And with regard to doing one's job, no one was under a greater microscope than FSU defensive coordinator Charles Kelly, whose first year in that position was met with derision by countless Seminole supporters. The calls to "Fire Kelly" were near ubiquitous after his rookie year as the ‘Nole DC, as fans pined for a return to the shutdown defense that led Florida State to its third national championship in 2013.

However, the prospect of Kelly departing was met with a different reaction after the lion's share of 2015 was in the books. For when Auburn, Kelly's alma mater, came calling late last year, many of those same Seminoles were clamoring about just what it would take to keep Kelly in Tallahassee.

And, as the numbers suggest, for good reason. Let's take a look at the substantial improvement Kelly's defense made in just his second year on the job.

Regardless of how you prefer to dissect a defense's performance, the end game is always to keep one's opponents off the scoreboard, and the ‘Noles were far better doing so in 2015 than in 2014. 2014 saw FSU finish tied for 50^th among FBS programs in scoring defense, at 25.6 PPG allowed, a far cry from the 2013 title-winning unit that topped the country at 12.1. In 2015, the Seminoles returned to the top-10, finishing ninth at 17.5.

Florida State limited opposing offenses' scoring chances by improving against both the run and the pass. On the ground, the ‘Noles went from 73^rd in 2014 (170.14 YPG) to 37^th in 2015 (145.31 YPG). And defending the aerial assault, FSU rose from No. 60 (226.8 YPG) to No. 21 (191.6 YPG), nationally.

A big part of the revamped pass defense can be attributed to the increased pass rush. While the Seminoles' defensive scheme does not necessarily place a premium on taking down the opponent's quarterback, Florida State nevertheless did so at a much higher rate in 2015 than in 2014, climbing from 17 sacks in 2014 (a tie for 108^th in the country) to nearly double that, with 32 in 2015 (tied for 31^st).

This helped FSU's third-down efficiency immensely. In 2014, ‘Noles opposition converted on 43.87% of third down tries, which was, again, ranked in triple digits at No. 106. In 2015 that percentage sank to 39.23%, a full 50 positions higher, at No. 66.

And the defensive leadership's emphasis on taking care of home seems to have had a great deal to do with these impressive upswings. Nothing gouges defensive stats like explosive plays that surrender massive chunks of yardage, and those are more apt to occur when defenders are out of position and off assignment. Yet those situations were few and far between under Kelly in 2015.

Concerning high-yardage running plays, the 2015 FSU defense allowed fewer plays of 10+ yards than the 2014 squad by a count of 61-80. The same is true for runs of over 20 yards, of which the 2015 unit conceded 11 compared to 2014's 17. Runs over 30 yards? Three in 2014—just one in 2015.

The big-play passes allowed speak even louder about the 2015 defense, which gave up 93 plays of 10+ yards, while the 2014 iteration saw 121 of the same variety. The 2015 Florida State defense also surrendered fewer passing plays of 20+ yards (33-51), 30+ yards (10-23), 40+ yards (4-11), and 50+ yards (3-6).

The point being, when opposing offenses did find success against Kelly's defense in 2015, it was in much smaller measures than in 2014. That, in turn, meant they had to line up and do it again against a side that was, for the most part, more talented, deeper, and as these numbers suggest, better coached.

After admitting that he felt the FSU defense "absolutely" had to improve from his first year to his second, Kelly underscored just how shortcomings early can foment success later on. Said Kelly of 2014: "We weren't happy with the way we played a lot of times." But he also acknowledged how that performance wasn't swept under the rug, but, rather, employed as motivation: "All successful teams, and all teams that do things above what they think they can do, they play with a chip on their shoulder, and I think that's something that you have to do."

Hence, Kelly and the defense did not just use 2014 as a rear-view contrast or cautionary tale—they took it with them, owned every shortcoming, and built on it to create the exceptional unit we witnessed in 2015.