Varsity Numbers: Four Truths Revisited
by Bill Connelly
As things currently stand, college football's Championship Week might be ... boring? The Iowa-Michigan State winner is in the playoff with a win, as are Clemson and Alabama in their respective conference championship games.
Now, every time we even begin to think something is going to go according to plan, hilarity ensues. So you can fully expect a run of last-second upsets now -- UNC over Clemson, Florida over Alabama, USC over Stanford. It is written.
But UNTIL those things happen, it's hard to write more than what I've already written about MSU-Iowa at SB Nation. So as we wait to analyze any potential wreckage that might come our way, I wanted to take another look at an old Varsity Numbers piece. I've been doing that randomly all season, and I have very much looked forward to coming around to this one.
One fun thing about the Internet is its archiving capabilities. Of all the ideas I've written about through the years, the Five Factors concept -- the idea that efficiency, explosiveness, field position, finishing drives, and turnovers are the backbone of football -- has perhaps resonated more than any. I'm proud of it, and I have enjoyed slowly peeling back the layers of what this might mean over the last couple of years.
Before Five Factors, though, there were Four Truths. This was one of my favorite first Big Idea posts at FO. And I wanted to revisit it to see how much my thinking has shifted over the last five years.
Truth No. 1: The old adage of "You can't win a game in the first quarter/half, but you can lose it," rings true.
If you run correlations between situational S&P+ statistics and win percentage, you see quite a few first- and second-quarter statistics near the top of the list. For instance, second-quarter Offensive S&P+ and first-quarter Defensive S&P+ had almost exactly the same correlation to winning as overall S&P+ did. From a statistical standpoint, the first half carries far more weight than the second, because, quite simply, with a bad first half, the second half might not matter much (unless you are Jacksonville State playing Ole Miss).
This is, of course, how sports mostly operate. We remember a given Game 7, but there would be no seventh game if you don't win three other games first. You probably don't pull off a dramatic, memorable overtime victory if you fall down by four touchdowns in the first half (unless your quarterback is Frank Reich). You don't notch the World Series-winning save in the ninth if you don't build a lead in the first eight (or eight and a half) innings. We remember the games that are decided late, but more often, the biggest impact on a game occurs in the first 30 minutes.
I kind of led with the weakest one.
This is something I've kind of let slide a bit. It makes plenty of sense, but "start a game well" doesn't necessarily fit on a list with "efficiency" and "finishing drives." And as the game picks up tempo, you have more time to catch up after a slow start.
Truth No. 2: Big plays win games.
The OPS measure in baseball is a direct split between on-base percentage and slugging percentage. It is a wonderful measure, but it is not quite as accurate as it could be, as on-base percentage matters more to good offense than slugging. The opposite is true in college football -- the explosiveness measure (PPP, the "slugging percentage" of the S&P equation) is almost always tied more closely to winning games than success rates (the "on-base percentage" piece). Both matter, but on offense and defense, PPP matters more.
Again, this is the way it should be. Nothing is more demoralizing than giving up a 20-play, 80-yard, nine-minute drive. But unless your team is Navy, that doesn't happen too often. Defensive coaches often teach their squads the concept of leverage -- prevent the ballcarrier from getting the outside lane, steer him to the middle, make the tackle, and live to play another down. It is the bend-don't-break style of defense, and it often works because if you give the offense enough opportunities, they might eventually make a drive-killing mistake, especially at the collegiate level. If you allow them 40 yards in one play, their likelihood of making a drive-killing mistake plummets.
Very true! But what I'm finding is that big plays are hard to replicate ... at least, the magnitude of big plays is.
Just as on-base percentage probably carries more heft than slugging percentage, it appears that efficiency (in this case, success rate) might be a steadier, stronger presence than explosiveness (IsoPPP). When I attempted to isolate the two factors from each other using IsoPPP, I found that efficiency was the far more stable and predictable of the two factors.
That makes sense, really. First of all, only "successful" plays can be explosive plays; second, magnitude can depend on field position, among other things. While some players/teams are clearly more explosive than others (Dalvin Cook), there is a randomness there that makes explosiveness a hard thing on which to rely.
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Truth No. 3: Leverage Rate gives us what we think we get from third-down conversion rate.
This is probably a less obvious truth. Announcers and coaches talk endlessly about how games are won and lost on third downs, and it is absolutely true. But it is also without context. Some defenses, particularly young ones, give up far too many demoralizing third-and-8 conversions. But most of the time, a team that allows a high third-down conversion rate is doing so because they're giving up too many yards on first and second down, and their opponent is converting third-and-3 instead of third-and-8.
The difference in the level of success on standard downs and passing downs is staggering. If you have a significant talent advantage -- always possible in college football -- you might be able to get away with falling into passing downs. But the team that wins is the team that better avoids passing downs. That is why Leverage Rate is included atop the Varsity Numbers box scores I analyze (now on Tuesdays). If your Leverage Rate is too far below the national average of 68 percent, then your quarterback better be Colt McCoy (who was truly a magician at converting third-and-7 and, it appears, masked some serious, developing deficiencies for Texas on the offensive side of the ball) or you are probably going to struggle to win.
Through the 2015 regular season, the correlation between your leverage margin (your leverage rate minus your opponent's) and whether you won or lost is 0.558. (By means of comparison, the correlation between points scored and whether you won or lost is only 0.623.)
Obviously the ideas of efficiency leverage are very much tied together. But if I could add just one thing to a given box score, assuming success rate isn't an option (and it obviously is not), it would be either average yards per play on first down or average yards to go on third. They tell us so much about what we think third-down conversion rate tells us.
Truth No. 4: Field position matters so very, very much.
So far in 2010, the winner of a given game typically runs 50.2 percent of their plays in their opponent's field position. For losing teams, it is 36.2 percent. That is why Field Position Percentage is above even Leverage Rate on the Varsity Numbers box score, and that is why Brian Fremeau's FPA statistic is so telling. Field position numbers fill in all of the gaps the other statistics miss. If you lose a game despite beating your opponent in both S&P (or total yardage) and turnovers, chances are that you badly lost the field position battle.
Winning the game of field position can be done in too many ways to count. Maybe you have an outstanding punter. Maybe you avoid three-and-outs and at least advance the ball a bit before punting. Maybe you have a good return man. Maybe you avoid turnovers. Whatever the cause, field position often matters as much or more than turnovers on the "What wins games" hierarchy. (Don't tell that to Arizona State, of course; they lost to Oregon last week because they lost the turnover points battle by 25.0 points.)
Some quick 2015 data:
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- If you win the field position battle by 0 to 5 yards per possession, you're winning 57 percent of the time by an average margin of 3.3 points.
- If you win the field position battle by 5 to 10 yards per possession, you're winning 77 percent of the time by an average margin of 13.0 points.
- If you win the field position battle by 10 to 15 yards per possession, you're winning 87 percent of the time by an average margin of 19.1 points.
- If you win the field position battle by 15 to 20 yards per possession, you're winning 94 percent of the time by an average margin of 24.3 points.
- If you win the field position battle by more than 20 yards per possession, you're winning 96 percent of the time by an average margin of 34.4 points.
Yeah, that definitely belongs on the Five Factors list.