Does the NFL Really Have Parity?

Posted Monday March 11, 2013 at 8:55:08 pm in Real Sports

We hear it all the time whenever a surprise team in the NFL does better than they are supposed to: the NFL has parity. But is that really the case?

I've compiled data from Pro Football Reference's site for all 32 NFL teams over the last 13 seasons (2000-2012) to try and determine what this "parity" term actually means in practice. For comparison's sakes, I've compiled data from Baseball Reference's site for all 30 MLB teams over the last 13 seasons (2000-2012). The results are pretty interesting.

***Please keep in mind that my data entry could be off, so if there's an error please contact me.

Playoffs

For the NFL, there are 32 teams in 8 different divisions in 2 different conferences. Each division leader plus 2 wild cards from each conference makes the playoffs for a total of 12 teams. This means right off the bat 37.5% of the teams in the NFL will make the playoffs. Compare this to MLB, which up until 2012 only had 8 teams out of 30 make the playoffs (~27%). In 2012 MLB added an extra Wild Card team for a total of 10 teams out of 30 (~33%).

To determine how much parity the NFL has, I'm going to use a few different guidelines, namely: playoff appearances and winning percentage.

2000-2012 Winning Percentage

NFL 

From 2000 to 2012 there have been 13 NFL seasons. There were 15 teams that maintained a > .500 winning percentage during this time span:

  • New England Patriots 0.70673
  • Indianapolis Colts 0.66346
  • Pittsburgh Steelers 0.65144
  • Green Bay Packers 0.62981
  • Baltimore Ravens 0.60577
  • Philadelphia Eagles 0.60337
  • Denver Broncos 0.56731
  • New York Giants 0.55769
  • New Orleans Saints 0.54808
  • Tennessee Titans 0.53846
  • Atlanta Falcons 0.53606
  • Chicago Bears 0.52885
  • San Diego Chargers 0.52404
  • Seattle Seahawks 0.51442
  • New York Jets 0.50481

Going off of winning percentage there are 6 teams over the course of the last 13 years with an elite 60% or better winning percentage: Patriots, Colts, Steelers, Packers, Ravens and Eagles. Only one team had a 70% or better winning percentage: the New England Patriots.

There was a single team with a perfect .500 record: the Dallas Cowboys. The Jets came pretty close with a 0.50481. This leaves 16 teams with a record under .500 during that 13 year span:

  • Minnesota Vikings 0.49519
  • Tampa Bay Buccaneers 0.48077
  • Miami Dolphins 0.47596
  • San Francisco 49ers 0.47356
  • Carolina Panthers 0.45192
  • Cincinnati Bengals 0.43990
  • Houston Texans 0.43750
  • Washington Redskins 0.43750
  • Jacksonville Jaguars 0.43750
  • Kansas City Chiefs 0.42788
  • St. Louis Rams 0.42067
  • Buffalo Bills 0.39423
  • Oakland Raiders 0.39423
  • Arizona Cardinals 0.38462
  • Cleveland Browns 0.34135
  • Detroit Lions 0.29808

You'll notice there are 2 awful teams: the Detroit Lions and the Cleveland Browns with the Arizona Cardinals, Oakland Raiders, and Buffalo Bills not too far beyond. These teams all had a winning percentage under 40%.

What you'll also notice are 2 teams with a 48% or better winning percentage under .500

MLB

During this same time span, MLB had 11 teams with a > .500 winning percentage:

  • New York Yankees 0.59505
  • St. Louis Cardinals 0.55914
  • Boston Red Sox 0.55487
  • Atlanta Braves 0.55418
  • Los Angeles Angels of Anaheim 0.54843
  • Oakland Athletics 0.54135
  • Philadelphia Phillies 0.53682
  • San Francisco Giants 0.53590
  • Los Angeles Dodgers 0.52732
  • Chicago White Sox 0.52634
  • Minnesota Twins 0.51542

Most of these teams hover around the 53%-56% winning percentage with the New York Yankees nearly hitting 60%.

The Texas Rangers almost have a perfect .500 record with a .50095 record. This leaves 18 teams with a record under .500:

  • New York Mets 0.49667
  • Arizona Diamondbacks 0.49620
  • Toronto Blue Jays 0.49596
  • Seattle Mariners 0.49383
  • Cleveland Indians 0.49050
  • Miami Marlins 0.49049
  • Houston Astros 0.48409
  • Cincinnati Reds 0.48338
  • Chicago Cubs 0.48194
  • San Diego Padres 0.47746
  • Milwaukee Brewers 0.47363
  • Detroit Tigers 0.47151
  • Colorado Rockies 0.46939
  • Tampa Bay Rays 0.46172
  • Washington Nationals 0.45532
  • Baltimore Orioles 0.44011
  • Pittsburgh Pirates 0.42273
  • Kansas City Royals 0.41880

What you will notice is that of the teams under .500, 9 of them hold a 48% or better winning percentage. You'll also notice not a single team under the 40% threshold. For the NFL there were 5 teams with a winning percentage under 40%. One of which had one under 30% (the Detroit Lions). 

Groups

You'll notice the swing over a 13 season period for the NFL is anywhere from 29.8% (Detroit Lions) to 70.6% (New England Patriots). The Patriots had nearly 2.4 times the winning percentage of the Detroit Lions. 

For MLB, the range is much smaller. The lowest? The Royals with 41.8%. The highest? The Yankees with 59.5%. That's really about 1.4 times the winning percentage. 

If we use the average winning percentage above .500 for the NFL, we find that value to be 0.579. We'll also use the average winning percentage below .500 for the NFL. That value is 0.424. This is a 15.5% swing.

Using these values we can categorize groupings as: Great, Good, Average, Bad, Awful

  • Great being any team with a winning percentage above 0.579
  • Good being any team with a winning percenatage below 0.579 and above 0.500
  • Average being 0.500
  • Bad being below 0.500 and above 0.424
  • Awful being below 0.424

Using those groupings, we find the following:

  • Great (6): Patriots, Colts, Steelers, Packers, Ravens, Eagles
  • Good (8): Broncos, Giants, Saints, Titans, Falcons, Bears, Chargers, Seahawks
  • Average (2): Cowboys, Jets
  • Bad (10): Vikings, Buccaneers, Dolphins, 49ers, Panthers, Bengals, Texans, Redskins, Jaguars, Chiefs
  • Awful (6): Rams, Bills, Raiders, Cardinals, Browns, Lions

For MLB, the average winning percentage above .500 is 0.541. The average winning percentage below .500 is .472. This is only a 6.9% swing. The NFL has a 15.5% swing, nearly 2.2 times MLB. 

We'll now use the following groupings: 

 Great, Good, Average, Bad, Awful

  • Great being any team with a winning percentage above 0.541
  • Good being any team with a winning percenatage below 0.541 and above 0.500
  • Average being 0.500
  • Bad being below 0.500 and above 0.472
  • Awful being below 0.472

Using those groupings, we find the following:

  • Great (6): Yankees, Cardinals, Red Sox, Braves, Angeles, Athletics
  • Good (5): Phillies, Giants, Dodgers, White Sox, Twins
  • Average (1): Rangers
  • Bad (11): Mets, Diamondbacks, Blue Jays, Mariners, Indians, Marlins, Astros, Reds, Cubs, Padres, Brewers
  • Awful (7): Tigers, Rockies, Rays, Nationals, Orioles, Pirates, Royals

Now, keep in mind that this is over the course of 13 seasons. I'll do another article using a smaller season sample size (5 seasons). 

But winning percentage is only one part of the equation. What about playoff appearances?

2000-2012 Playoff Appearances

NFL

As said above, 12 out of 32 teams in the NFL make the playoffs. But how many times have each team made the playoffs in the last 13 seasons?

  • Indianapolis Colts 11
  • Baltimore Ravens 10
  • New England Patriots 10
  • Philadelphia Eagles 9
  • Green Bay Packers 9
  • Pittsburgh Steelers 8
  • Seattle Seahawks 7
  • New York Giants 7
  • Denver Broncos 6
  • Atlanta Falcons 6
  • New York Jets 5
  • San Diego Chargers 5
  • Tampa Bay Buccaneers 5
  • Tennessee Titans 5
  • Minnesota Vikings 5
  • New Orleans Saints 5
  • Chicago Bears 4
  • Cincinnati Bengals 4
  • Dallas Cowboys 4
  • San Francisco 49ers 4
  • St. Louis Rams 4
  • Oakland Raiders 3
  • Washington Redskins 3
  • Miami Dolphins 3
  • Carolina Panthers 3
  • Houston Texans 2
  • Jacksonville Jaguars 2
  • Kansas City Chiefs 2
  • Arizona Cardinals 2
  • Cleveland Browns 1
  • Detroit Lions 1
  • Buffalo Bills 0

Every team in the NFL has made the playoffs at least once in the last 13 seasons except for the Bills. 11 is the most, 0 is the least. Being that ~38% of the teams make the playoffs each year over the course of 13 seasons...we can feel safe using something like 4.875 (5) as the middle ground in a perfect world for the number of times a team should make the playoffs over that year span. This is a simple calculation (13 seasons * 37.5%).

Using similar logic for winning percentage categorization, we find that the average playoff appearances above 5 is roughly 8. Average playoff appearances below 5 is 2.63 (3).

We'll categorize (once again): Great, Good, Average, Bad, and Awful.

  • Great (6): Colts, Ravens, Patriots, Eagles, Packers, Steelers
  • Good (4): Seahawks, Giants, Broncos, Falcons
  • Average (6): Jets, Chargers, Buccaneers, Titans, Vikings, Saints
  • Bad (9): Bears, Bengals, Cowboys, 49ers, Rams, Raiders, Redskins, Dolphins, Panthers
  • Awful (7): Texans, Jaguars, Chiefs, Cardinals, Browns, Lions, Bills

MLB

Up until 2012 only 8 teams out of 30 made the playoffs each year. Since 2000, the following is a playoff breakdown:

  • New York Yankees 12
  • St. Louis Cardinals 9
  • Atlanta Braves 8
  • Los Angeles Angels of Anaheim 6
  • Minnesota Twins 6
  • Boston Red Sox 6
  • Oakland Athletics 6
  • San Francisco Giants 5
  • Philadelphia Phillies 5
  • Los Angeles Dodgers 4
  • Arizona Diamondbacks 4
  • Chicago White Sox 3
  • Detroit Tigers 3
  • Houston Astros 3
  • Tampa Bay Rays 3
  • Texas Rangers 3
  • Chicago Cubs 3
  • Cincinnati Reds 2
  • San Diego Padres 2
  • Colorado Rockies 2
  • Seattle Mariners 2
  • Milwaukee Brewers 2
  • New York Mets 2
  • Cleveland Indians 1
  • Washington Nationals 1
  • Miami Marlins 1
  • Baltimore Orioles 1
  • Pittsburgh Pirates 0
  • Kansas City Royals 0
  • Toronto Blue Jays 0

What you'll see are 3 teams that haven't made the playoffs since 2000: the Pirates, Royals, and Jays. In a league where ~27% teams make the playoffs (versus the NFL's 38%), only 3 teams haven't made the playoffs in the last 13 seasons. Keep in mind that MLB is also a league without a salary cap, although there are some policies in place to keep things as competitive as possible without instituting a cap.

Anyways, assuming a 27% percentage over 13 seasons, the average number of appearances should be around ~3.5 (if we use 8 out of 30, it's actually something like 26.66%, but we'll use 27%). So we'll use 3-4 appearances as average. This means the average number of appearances over 4 is 7 and the average number of appearances below 3 is 1.2 (effectively 1). So great would be playoff appearances over 7, good (< 7 and > 4), average (3-4), bad (< 3 and > 1), and awful (<= 1)

We'll categorize (once again): Great, Good, Average, Bad, and Awful.

  • Great (3): Yankees, Cardinals, Braves 
  • Good (6): Angels, Twins, Red Sox, Athletics, Giants, Phillies 
  • Average (8): Dodgers, Diamondbacks, White Sox, Tigers, Astros, Rays, Rangers, Cubs 
  • Bad (6): Reds, Padres, Rockies, Mariners, Brewers, Mets
  • Awful (7):  Indians, Nationals, Marlins, Orioles, Pirates, Royals, Jays

What we see here is that there are 9 teams above average, 8 teams average, and 13 teams below average in MLB.

For the NFL there are 10 teams above average, 6 teams average, and 16 teams below average. This is very similar to MLB. 

Wrapping Up

This is a large sample size when it comes to professional sports. In 13 seasons a lot of things can change, so I'd like to do a follow up using a 5 year sample size.

That said, what we have found out here are the following key points:

  • ~38% of NFL teams make the playoffs every year
  • Up until 2012, only 27% of MLB teams make the playoffs every year
  • When using winning percentage, there are 6 great teams in the NFL and 8 good teams for a total of 14.
  • When using winning percentage, there are 6 great teams in MLB, and 5 good teams for a total of 11.
  • When using winning percentage, there are 10 bad teams and 6 awful teams in the NFL for a total of 16.
  • When using winning percentage, there are 11 bad teams and  7 awful teams in MLB for a total of 18.
  • When using playoff appearances, there are 6 great teams and 4 good teams in the NFL for a total of 10.
  • When using playoff appearances, there are 3 great teams and 6 good teams in MLB for a total of 9.
  • When using playoff appearances, there are 9 bad teams and 7 awful teams  in the NFL for a total of 16.
  • When using playoff appearance,s ther eare 6 bad teams and 7 awful teams in MLB for a total of 13.
  • 1 NFL team hasn't made the playoffs in 13 seasons (the Bills)
  • 3 MLB teams haven't made the playoffs in 13 seasons (the Pirates, Royals and Blue Jays). 

What we have found out (according to winning percentage) that in a league with a salary cap (the NFL) there still are nearly the same amount of bad/awful teams (16) as a league without a salary cap (MLB - 18 teams). Furthermore, the number of above average teams is nearly similar as well (NFL - 14, MLB - 11).

It's even closer when you use playoff appearances, which is rather surprising. Above average teams? 10 for NFL, 9 for MLB. Below average? 16 for NFL and 13 for MLB. 

A future blog post will use a smaller sample size (something like 2008-2012).

***If you'd like to see the data, I have 2 small MySQL databases (one for NFL, one for MLB) and a few SQL statements (for calculating winning percentage, average winning percentage, etc.). I'll provide it on request. Just contact me.

The opinions expressed herein are my own personal opinions and do not represent my employer’s view