Friday, August 10, 2012

NFL: The Biggest Indicator/Statistic in Projecting Team Success, Both Straight Up & ATS

How about that title?  That is saying a lot, isn’t it?  But this one statistic is that important, it is that HUGE in determining the outcomes of NFL games.  What is it?  Its yards per passing attempt (YPA).
I didn’t notice many discussing this statistic about 5 years ago when I started crunching the numbers, and really touting its importance whenever, wherever I could.  And year after year, season after season, this metric is about as close to a “LOCK” as you can get when talking NFL statistics and their correlation to points scored, which leads to SU wins/losses, and ATS win/losses.  There really are so many angles to take when simply using this one statistic, but let’s start by combining this metric with TOM, and show how critical those two combined are to a team’s performance.
How rare is it for a team to win a game, but lose both of those statistics in that same game?  The answer is it’s extremely rare, almost unfathomable to absorb how critical it is for a team to excel in both those areas.  To show the point, let’s go back the last 3 seasons, and show how many times it occurred – a team winning the game, but being negative in TOM and NET YPA:
DEN 24-22
SF 25-19
NO 40-33
NO 27-16
NE 20-16
HOU 20-19
NYJ 27-24
NYJ 28-24
STL 13-12
SD 20-17
ARI 23-20
DAL 20-19
NO 16-14
PHI 38-31
NE 23-20
CHI 23-6
MIA 10-6
HOU 30-27
ARI 24-23
SD 33-25
CLE 41-34
TEN 20-17
IND 28-16
OAK 20-19
DAL 7-6
CAR 28-21

Believe it or not, there is every game over the last 3 seasons where a team won the game SU, yet lost both TOM and YPA in the same game.  As a reminder, there are 256 wins per season; since we are looking at three years here multiply that by 3 which equals 768 wins for this analysis.  Of those 768 winners only 26 of them were won by a team that lost both the TOM and YPA in that same game.  That equals 3.4% of the games played over the last three years!  Wow!  How correlated are those two stats with wins and losses?  That is truly amazing.
Now, let’s move on to breaking down YPA on its own, as simply by itself it has an enormous correlation to success, which is ultimately generated by points scored and allowed.
Over the same 3 seasons, 45 of 47 teams that have finished with a NET POSITIVE YPA (Offensive YPA minus Defensive YPA) have had an 8-8 or better record that season.  Who are the two teams that missed the mark?  The 2009 Washington Redskins, who were 6.01 OFF YPA, 5.89 DEF YPA for a NET YPA of +0.12 – that is narrowly in the positive category, and WAS went 4-12 that season.  The other team was the 2010 Tennessee Titans, who were 6.36 OFF YPA, 5.96 DEF YPA for a NET YPA of +0.39 – they went 6-10 that season. 
What’s more, again examining the last 3 seasons, here are the team’s that were positive in YPA each year, and where they rank in wins during that same period:

Check that matrix out, and again, look how solid this metric is for identifying the best teams in the NFL (the green highlighted teams are who won the last 3 Super Bowls).  The Top 5 teams in the NFL were all positive in NET YPA over each of the last 3 seasons, along with 7 of the top 8 and 8 of the top 10.  What teams are missing from the top 10? 
  • ATL is #6 in wins over the last 3 years, but has actually been negative in NET YPA in 2 of the 3 years – is it a coincidence ATL has flamed out in the playoffs dramatically in their only two appearances in the last three years? 
    • 2009 they missed the playoffs, and had their worst YPA during the period discussed
    • 2010 they were the NFC’s #1 seed, winning 13 games despite ranking 19th in NET YPA at a negative 0.41.  What happened in playoffs?  They were promptly hammered at home in their opener 48-21 by eventual champ GB, who was ranked #2 in NET YPA
    • 2011 was the only of the three where they actually finished positive in YPA at a solid +0.7, ranking them #10 in the NFL.  They made the playoffs with 10 wins, but were forced to travel to NY to face the Giants despite the Giants having one less win on the season.  What happened on that day?  They were again hammered in ugly fashion losing 24-2, yielding 277 passing yards, not breaking 200 yards passing on their own despite having 9 more attempts. 
    • After seeing these numbers it’s hard to imagine it’s a coincidence. 
  • NYJ are #9 in wins over the last three seasons, and once again, their YPA statistic tells their story.  They were positive NET YPA in 2009 & 2010, but last year fell to the negative range.
    • 2009 the Jets were +1.09 (#11), tied for #11 in wins with 9, made the playoffs and advanced to the AFC Championship game where they lost to IND, who was ranked #2 in NET YPA. 
    • 2010 again the Jets checked in at #11 in NET YPA, again advanced to the AFC Championship game where they lost to PITT, who was ranked #3 in NET YPA. 
    • 2011 they finished -0.2 in NET YPA, which is why they were excluded from the matrix above, and not coincidentally they missed the playoffs.
    • Like ATL discussed above, the NYJ’s success or failure could directly be linked to their performance in the NET YPA statistic.
Now that we have discussed NET YPA some, and showed some great examples how useful that statistic is, let’s focus on offensive YPA, which is definitely more impactful compared to defensive YPA.  The first angle I will present is by year some key trends within the OYPA data:
  • 2009: top 16 were all at least 8-8
  • 2010: 9 of the top 11 were at least 8-8.  The two outliers were:
    • Houston Texans: checked in #4 with a 7.03 OYPA, but only came up with 6 wins.  When taking a closer look at HOU, what immediately stands out is 2010 was their worst OYPA of the 3 seasons – in 2009 they were 7.54/#4 and won 9, and in 2011 they were 7.33/#6 and won 10 games.  But, with only a modest dip in the true #, how can we explain the severe drop-off in wins?  A very poor overall defense is the answer.  HOU’s defense in 2010 was the worst in the NFL according to my #’s, as they were rated #31 in pass defense, #31 in my miscellaneous defense category (which is stats such as first downs, time of possession – any stat that cannot be directly linked to either passing or rushing), and #22 in rush defense.  Also, since this is a YPA article, they were #31 in DYPA, only behind JAC.  Lastly, also chipping in was an SOS I had rated 5th toughest in the NFL.  So although their OYPA metric was that of a solid, playoff type team, their defense was so weak and their SOS so strong their OYPA could not make up for its deficiencies. 
    • Dallas Cowboys: checked in #7 with a 6.77 OYPA, but only came up with 6 wins.  That # by itself is that of a borderline double digit win team, but DAL in 2010 fell 3-4 wins short of what the expected result would be strictly using OYPA.  What drove them down?  Similar to HOU, but not as dramatic, was a defense that was rated #20, including #27 vs. the pass and #21 in miscellaneous categories.  They also really struggled in DYPA checking in @ #28 in the NFL, which by itself isn’t a death sentence, but when combined with poor defense all around it is more heavily impactful.  DAL was also the worst in defensive efficiency, as measured by yards per point.  So to summarize, like HOU, it was a clear lack of defensive prowess that cost them in 2010.
  • 2011: top 12 were all at least 8-8
  • Summary: If you look at the top 11 teams each year in OYPA since the 2009 season, 31 of the 33 finished at least 8-8.  Get that OYPA up and your chances of reaching the playoffs dramatically increases.
Lastly, let’s move to defensive YPA.  Although when testing statistically it does not have quite the same impact on results as OYPA does, it is still useful and clear trends can be seen in the data.  Here are the key trends in DYPA over the last 3 seasons:
  • 2009: 10 of top 11 were at least 8-8.  The outlier was:
    • Buffalo Bills: BUF had an average defense (#16 in my ratings) which was buoyed by a strong performance in DYPA (#2) allowing just 5.10ypa.  If this were OYPA that ranking would certainly mean playoffs, but for BUF in 2009 it didn’t quite make that mark winning only 6 games.  One of the major reasons was an SOS that I rated #4, while the biggest reason was an offense that was rated #29 in my performance ratings, only ahead of CLE, DET and OAK.  Amazingly, in the 18 stats I track per game per team, BUF did not break the top 12 in any of them offensively, and finished #25 or worse in 14 of the 18!  That shows right there why they fell well below where their DYPA # would suggest, even including the fact they were jolted favorably by a TOM that was #11 in the NFL.
  • 2010: 8 of the top 9 were at least 8-8.  The outlier was:
    • St. Louis Rams: only fell one game short of the .500 mark, and they lost their final game of the regular season in SEA when the division crown was on the line.  STL had the #8 DYPA this season, which almost vaulted them to a surprising division crown – even if it was only the NFC West.  Not surprising, their offense was behind their defense in 2010, as rookie Sam Bradford took a bulk of the snaps leading to the #25 offense in the NFL.  The Rams finished #24 rushing, #25 passing and #20 miscellaneous in my ratings, along with #26 in efficiency – all major reasons why they needed that final game victory to win the NFC West.  Had they played a little better offensively, including OYPA that was a miserable 30th in the NFL, it may have earned that playoff bid that ever so slightly eluded them.
  • 2011: top 9 were all at least 8-8
  • Summary: If you look at the top 9 teams each year in DYPA since the 2009 season, 25 of the 27 finished at least 8-8. 
YPA, especially NET YPA, but also OYPA and to a lesser degree DYPA all have significant impacts on the success of NFL teams.  You saw all the numbers above, and they pretty much came to a conclusion that the better you are in NET YPA, the more likely you make the playoffs.  And any team that can come up with a top 10-ish YPA, whether OFF or DEF has a very good chance at making the playoffs – or at the very least being in the mix as the calendar turns to December.

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