Heading into the NFL playoffs, each playoff team’s offense and defense will be subject to even more detailed evaluation than usual.
The traditional statistics used to evaluate NFL teams’ offenses and defenses are based on yardage, which is an incomplete measure for many reasons.
Going beyond the box score and looking at what has actually happened on every play where a given unit was on the field (using expected points added, or EPA) results in a much more accurate evaluation of that unit’s complete contribution to the scoreboard, and therefore, winning and losing.
Below are a few examples of offenses and defenses that will be taking the field this weekend whose quality is misrepresented by their yardage rankings.
Because playoff teams are generally good, the biggest differences come when looking at units that are underrated by their yardage-based ratings. If these units were actually as bad as the yardage rankings indicate, the teams would have had much less chance of making the playoffs at all.
Indianapolis Colts Offense (15th in YPG, 6th in EPA PG)
Based on the Indianapolis Colts' 342 yards per game, the offense looks average. But Andrew Luck and company have been really great at limiting mistakes, committing just 13 offensive turnovers (three fewer than any other team in the league) and being penalized for just 14.7 yards per game while on offense (also least in the league).
Colts Offense - 2013 Season
On a related note, the Colts offense has drawn a lot of penalties, earning 40.3 yards and 2.4 first downs per game due to calls on the opposing defense (both ranked in the top-5 in the NFL).
With that additional yardage not accounted for in “total offense” and the fact that the Colts have done well converting their yards into points - averaging 5.0 points per red zone trip - it makes sense that their offense rates near the top of the NFL in terms of EPA.
Philadelphia Eagles Defense (29th in YPG, 15th in EPA PG)
It seems difficult to believe that a team with the “fourth-worst defense” in the NFL, giving up nearly 400 yards per game, could have gone 10-6. And that’s because in actuality, when you take into account everything they do to impact the scoreboard, the Philadelphia Eagles defense hasn’t been the fourth-worst in the NFL.
First off, there is the pace issue. Because of Chip Kelly’s fast offense, the Eagles defense was on the field a lot – a league-high 1,150 snaps, to be exact – so it’s not fair to compare them to others using total yardage.
Eagles Defense - 2013 Season
Looking on a per-drive basis, the Eagles still allowed a decent amount of yardage but tightened up in the red zone and limited opponents to just 1.74 points per drive overall, slightly better than the league average.
The Eagles defense forced 31 turnovers (tied for third in the NFL) that contributed to preventing points and also helped set up their own offense. Putting it all together, the Eagles defense certainly isn’t elite, but it ranks right around the league average – much better than the yardage numbers indicate.
Kansas City Chiefs Defense (24th in YPG, 8th in EPA PG)
The Kansas City Chiefs defense definitely performed much worse as the level of competition stepped up dramatically in the second half of the season, but they were nowhere near a bottom-10 defense as the full-season yardage numbers indicate.
The Chiefs wiped away a lot of the yards they allowed by forcing turnovers and turning them into points or great field position for the offense.
Chiefs Defense- 2013 Season
Not only were the Chiefs second in the NFL with 33 turnovers forced and tied for first with six defensive scores, but they were also great at setting up their offense with great field position.
On possessions following turnovers and turnovers on downs (times where the defense directly “set up” the offense), Alex Smith and company came onto the field with an average field position on the opponents’ 39, the best such average of any team in the league by more than five yards.
In large part because of all those turnovers, the Chiefs allowed just 1.5 points per drive, good enough for fifth in the NFL.
Put it all together and the poor yardage ranking is way off – the Chiefs defense was a net positive for the team, adding nearly three points per game to the scoring margin and helping them get to 11-5 and a Wild Card berth.
San Francisco 49ers Offense (24th in YPG, 13th in EPA PG)
The San Francisco 49ers defense is the main strength of the team no matter what stat you use, but if you just looked at the yardage numbers, it would be appear that the team was succeeding in spite of the offense.
Part of the reason is the 49ers offense is one of the slowest in the league, averaging 40.6 seconds between line-of-scrimmage plays, fourth-most in the NFL. As a result, the 49ers average just 60 snaps per game, second-fewest in the league, and therefore it makes sense they don’t rack up quite as many yards as other teams with more plays.
49ers Offense- 2013 Season
Like the Colts, the 49ers have done a good job limiting turnovers, with only 18 offensive giveaways all season and none being returned directly for scores.
Colin Kaepernick and crew have done a good job making the most of the yards they do get, scoring on 79 percent of drives inside the opponents 40 (third-best in the NFL) and averaging five points per trip into the red zone.
Looking at the overall contribution of the San Francisco offense, it is actually above average at nearly three net points per game.