Why does elite recruiting help college football defenses more than offenses?

For the most part, we've accepted it. Recruiting rankings matter. Star ratings are just accurate enough to mean something, and you're probably not winning the national title without a lot of them.

Are the grading systems by Rivals, Scout, ESPN, and 247Sports infallible? Of course not. Is there a bit of a circular relationship between success and signing good classes? Absolutely. But on average, you can build a pretty good predictive model based solely on classes. Signing a better class improves your odds of putting a better product on the field.

It's step one, anyway. After you've acquired the talent, you have to develop it and deploy it.

Those steps trip plenty of teams up. Using the two-year recruiting rankings I developed for my offseason previews, you can see recruiting isn't everything. No. 2 on the two-year recruiting list: 8-6 USC. UCLA was fourth, Auburn fifth, Tennessee sixth, Texas A&M eighth, and Georgia 10th.

Meanwhile, Michigan State (22nd in two-year recruiting), North Carolina (25th), Baylor (32nd), Oklahoma State (33rd), Wisconsin (35th), Northwestern (40th), TCU (49th), Utah (51st), and Iowa (56th) won 10-plus games in major conferences without being elite on Signing Day. Michigan State reached the Playoff after beating two of those top recruiting teams; Oregon made the Championship a year ago.

Still, recruiting rankings are about odds. Better classes mean better chances of success.

Here's a look at 2015's top 10 teams, according to S&P+, and their two- and five-year recruiting rankings (per a custom, percentile-based blend of Rivals and 247Sports) from before the season began.

	Record	2015 S&P+	S&P+ rank	2-year rec. rank	5-year rec. rank
Alabama	14-1	30.0	1	1	1
Clemson	14-1	27.4	2	12	14
Ohio State	12-1	24.0	3	9	4
Oklahoma	11-2	22.6	4	16	12
Ole Miss	10-3	21.2	5	21	21
Michigan	10-3	21.1	6	14	11
Florida State	10-3	20.0	7	3	3
Notre Dame	10-3	18.8	8	11	10
LSU	9-3	18.6	9	7	5
Stanford	12-2	18.4	10	17	15

The only top-10 team that hadn't recruited at a top-15 level over the previous five years was Ole Miss, which signed the No. 8 class in 2013 and the No. 15 in 2014 (and is close to inking a top-five class in 2016).

Okay, great, the rankings matter. But how do they matter?

They're likely to improve your overall product, but can we find evidence of the type of help they give you? To explore this question, let's look at the squared correlation value (the higher, the more correlation) of recruiting rankings and opponent-adjusted offensive and defensive stats.

Offensive stat	2-yr recruiting	5-yr recruiting	Defensive stat	2-yr recruiting	5-yr recruiting
Off. S&P+	29.4%	29.2%	Def. S&P+	41.5%	39.6%
Rushing S&P+	22.7%	22.1%	Rushing S&P+	22.1%	21.1%
Passing S&P+	23.9%	24.5%	Passing S&P+	38.9%	36.8%
Std. Downs S&P+	24.3%	24.0%	Std. Downs S&P+	31.6%	30.0%
Pass. Downs S&P+	24.0%	24.5%	Pass. Downs S&P+	31.1%	29.4%
Success Rate+ (efficiency)	28.0%	27.9%	Success Rate+	31.2%	30.5%
PPP+ (explosiveness)	27.1%	27.0%	PPP+	35.5%	33.3%
Adj. Line Yards	20.9%	20.2%	Adj. Line Yards	19.1%	18.1%
Adj. Sack Rate	0.2%	0.3%	Adj. Sack Rate	8.1%	7.6%

This gives us some hints about how recruiting matters most.

(Granted, if you sign a class heavy on defensive tackles, running backs, and offensive linemen, your rushing numbers are more likely to be impacted than your passing numbers. Or if you sign a class with 16 offensive players and only eight defensive players, that will probably have a specific effect, too. And great recruiting is likely to help your overall depth and athleticism above all else. That might mostly impact every category. Except your offense's sack rates, apparently.)

Hint No. 1: Raw talent might matter more on defense.

The correlations between recruiting rankings and defensive success were stronger than on offense. Whereas most offensive categories ended up in the 22 to 29 percent range, a majority of defensive categories were between 31 and 42 percent.

These are verified to some degree with eyeballing. Of the top five offenses according to Off. S&P+, only one (Stanford's) came from a team that recruits at a top-20 level. The other four were Arkansas (28th in two-year recruiting), Baylor (32nd), Texas Tech (47th), and Western Kentucky (93rd).

Meanwhile, four of the top six defenses came from the top end of the talent pool: Alabama (first in two-year recruiting), Michigan (14th), Clemson (12th), and Florida (13th). Boston College (53rd) and Northwestern (40th) bucked that trend.

This might make sense. Offensive innovation usually precedes defensive adjustment, so perhaps coaching, system, scheme, play-calling and development make more of a difference for the offense. Defense might be swayed more by pure athleticism and ready-made talent.

Then there's the matter of quarterback. Experience can be a great equalizer. If you sign a blue-chip signal caller, you might be more likely to play him as a really young QB. This can pay off, but for every Jameis Winston or Johnny Manziel, there's a blue-chip freshman who plays like a freshman.

Of the 20 freshmen in the top 10 of 247Sports' 2015 lists of pro-style and dual-threat QBs, seven played significant roles: UCLA's Josh Rosen, Washington's Jake Browning, Missouri's Drew Lock, Boise State's Brett Rypien, Texas A&M's Kyler Murray, Baylor's Jarrett Stidham, and South Carolina's Lorenzo Nunez. Of these, only one played for a top-20 offense: Stidham, who got hurt in his second start.

It's a similar story for 2014. On the dual threat list, you had Clemson's amazing Deshaun Watson, but you also had hit-or-miss guys like Texas' Jerrod Heard, LSU's Brandon Harris and Louisville's Reggie Bonnafon. For the pro-stylers, you've got guys who occasionally looked the part as freshmen (Miami's Brad Kaaya, Texas A&M's Kyle Allen, Florida's Will Grier) and guys who still have a lot of developing left (Kentucky's Drew Barker, Auburn's Sean White).

If you get a sports car at quarterback, you're going to take it for a drive soon ... and you're probably going to encounter a learning curve. Meanwhile, if your freshman pass rusher understands his role, all he has to do is attack.

Hint No. 2: Recruiting impacts passing more than rushing.

More specifically, it impacts pass defense more than run defense.

• The top 10 run defenses according to S&P+: Alabama, Boston College, West Virginia, Utah, Florida, Oklahoma, Louisville, Baylor, Akron, and San Diego State. Only three ranked in the top 16 in two-year recruiting.
• The top 10 pass defenses according to S&P+: Alabama, Texas A&M, Clemson, Ohio State, Florida State, Oklahoma, Florida, Penn State, Wisconsin, and Michigan State. Seven are in the top 16 in two-year recruiting, and all are in the top 35.

Results were similar in 2014. TCU, Missouri, and Virginia were among the top 10 run defenses, while the top 10 pass defenses were elite recruiters and Virginia Tech.

This might also make sense. If we are to believe that linemen are the most difficult players to project at the high school level -- since some will need to put on quite a bit of good weight (or take off some bad weight), and since their physical abilities alone made them unstoppable at the high school level -- then perhaps raw talent makes a big difference in the secondary, while development and scheme matter more up front.

Alabama is both proof of and an exception to this idea. The Tide have perpetually recruited well under Nick Saban, but pass defense was their biggest weakness in 2013 and 2014. Then, with five-star freshmen Marlon Humphrey and Minkah Fitzpatrick added, they fielded the best pass defense in college football. Individuals matter and recruiting rankings are not infallible ... but they were damn accurate when it came to Humphrey and Fitzpatrick.

Hint No. 3: Coaches control sacks.

If you're the coach of a team that doesn't recruit at a top-15 level, you might be most interested in where the correlations are low.

Without top recruiting, you might find development matters above all else on offense. You might be able to hone successful players up front and field a good run defense. You might have to protect your secondary. And you might notice that you have almost complete control over sacks.

On offense, so much of a team's sack rate depends on intent. You can neutralize a decent pass rush with quick passing and instructing your quarterback to throw the ball away at the first sign of trouble. On defense, you choose to blitz frequently or not at all, and as with run defense, you dictate how many line up near the line of scrimmage.

Individual talent will still play a role. Quarterbacks who move around or have receivers who get open quickly will better avoid sacks, and all-world pass rushers (and former four- or five-star recruits) like Clemson's Shaq Lawson, Texas A&M's Myles Garrett, Alabama's Jonathan Allen, Maryland's Yannick Ngakoue and Tennessee's Derek Barnett can give your pass rush an immediate boost.

Still, Air Force had the No. 2 pass rush in the country this season according to Adj. Sack Rate, in part because of sheer aggressive scheming. And while the list of the country's top pass rushers includes blue chips, it also includes Penn State's Carl Nassib, a former walk-on, and three-stars like Oklahoma State's Emmanuel Ogbah, Clemson's Kevin Dodd and Pitt's Ejuan Price.

Sacks aren't the only negative plays you can encounter or enforce, but they are to some degree controlled by coaching, not by sheer talent.