NFL Rankings, Week 8

This week I am going to take a page out of the Fox News playbook.

Hey?  Where are you going?  Don’t worry, I’m not going to try to sell you Food Insurance.  I just want to focus this week’s discussion on the key battleground divisions the way news networks look at swing states while ignoring the rest of the country.  So Rams fans can breathe easy, I won’t be taking so many shots at your team this week.  Besides, you should all still be celebrating the (baseball) Cardinals victory!

Battleground Division #1 – NFC North

The NFC North is stacked with talent this year, led by the Super Bowl champion and The Power Rank leader Green Bay Packers (#1, 11.55).  Normally having a team like the Packers in a division would settle matters, but this year it does not.  The reason is that the Lions (#4,  5.17) are right on the Packers’ heels, and the Bears (#9, 3.78) are not that far behind.  That’s three top ten teams in one division.  The Lions may have a hard time keeping up their pace especially with their oft-injured quarterback having ankle problems last week, and the Bears are legendary for pulling wins out of thin air.  Just ask Dennis Green!  Even if the Packers’ high level of success continues and they lock up the division title early, the Bears and Lions will both still likely be in the playoff hunt, in fact if the playoffs started today both teams would receive a wildcard berth.  With a lot of division games left the NFC North division is going to be an interesting one to watch.

Battleground #2 – AFC North

What’s with the North being so good at football?  Although the AFC North doesn’t feature three top ten teams as the NFC North does, it comes very close.  This division is led by the Baltimore Ravens (#3, 7.80) but they are actually a half-game behind the Steelers (#11, 2.58) and only a half game ahead of the Bengals (#12, 1.69).  Now, I know nobody talks about the “top twelve” of any lists, but it is nonetheless impressive that this tight grouping all falls within the top 12 teams in The Power Rank.  It’s hardly a revelation to NFL fans that the Steelers and Ravens are going to be battling for a division title, or that the loser is likely to grab a wildcard spot.  What is unlikely is the upstart Bengals sticking their noses into the mix.  With a third solid team to contend with the Steelers and Ravens will not be able to take anything for granted this season, and the fight for a playoff berth may get ugly in this division that is known for misconduct both on and off the field.

Battleground #3 – NFC East

The NFC East doesn’t carry nearly as many strong teams as the NFC and AFC North divisions do, but with some schedule oddities the team that The Power Rank picks as the clear division favorite is lagging behind in the actual standings.  The Cowboys (#8, 3.85) should be running away with this division in light of the fact that their closest competition should be the Eagles (#18, -0.89) who are also struggling to find wins.  Instead the Giants (#24, -3.29) are leading the division with a 4-2 record.  True, it’s early in the season.  And yes, we at The Power Rank do think that as things shake out the Cowboys’ record will start to match their apparent strength.  Even so, with poor starts from teams with high expectations and surprising starts from teams with low ones, everyone is in the mix here and every game is going to be an especially heated contest.

Non-Battleground – AFC East

The Power Rank is scheduled to get some East Coast bias with our next software upgrade.  If you want to hear how this is the only division that matters this year (or any other) tune into ESPN.  We apologize for the inconvenience.  Sure, the AFC East has a lot of strength in top ten teams New England (#2, 9.77) and New York (#7, 4.36) but in spite of what some sports news anchors would have you believe, this is not news.  The addition of the up and coming Bills (#16, 0.41) is shaking some fans’ confidence in the Patriots and Jets getting their perennial playoff spots, but The Power Rank thinks otherwise.  The Bills are indeed a good team right now but good is not enough in a division that has contained two top ten (and usually top five) teams for the last few years.  This division will get down and dirty where it normally does (in the playoffs) with the teams it normally sends (the Pats and Jets).  Until then, my attention will be elsewhere.

NFL Prediction, Conference Championships

Green Bay will beat Chicago by 2.7 on the road

Pittsburgh will beat New York Jets by 3.8 at home

The predictions were 1 of 2 last weekend in the Divisional Playoff games. We won on Green Bay, lost on the New York Jets, and chose not to bet on the other two games.

Defense wins championships… or does it?

For new readers of The Power Rank blog, here’s a brief summary of the week four posting:

“If political strategist James Carville were an NFL pundit he might be telling us ‘It’s the defense, stupid!'”

At that time, the top teams in the Power Rank were defensive powerhouses, with the exception of the then and now offensively dominant New England Patriots.

Now that the NFC and AFC championship games are looming on the horizon, it is again apparent that strong defense is the key to success in the NFL.

The four teams that remain in the Super Bowl hunt are the Steelers, Packers, Bears and Jets.  All of these teams were defensive juggernauts this year.  In the regular season, they ranked 1st, 2nd, 4th, and 6th respectively in points allowed.   What happened to teams in 3rd and 5th place?  Last weekend the 3rd place Ravens lost to the 1st place Steelers, and the 5th place Falcons lost to the 2nd place Packers.

Just take a look at the how the top ten teams in The Power Rank correlate to their rank in points allowed during the regular season:

First, it’s clear that being highly ranked defensively was critical to making the top of The Power Rank this year.  More importantly notice the teams that made the playoffs, and teams still alive in the playoffs…  all of the teams that are still playing have elite defenses, but with the Patriots’ loss on Sunday the best offense left is that of the Packers, the 10th ranked offense in the league.

To see if this was a more universal truth of the NFL, I decided to do some more digging into the success of superior defensive teams in the playoffs.  I started with playoff results by defensive rank since 2002:

Not all seasons have been dominated by defensively superior teams, but overall there is definitely an emerging trend.

While compiling these stats I also noticed that there were a large number of games where teams played opponents of very similar defensive caliber.  It didn’t seem right to me that a 3rd ranked defense beating a 2nd ranked defense be considered the same as a 10th ranked defense beating a 2nd ranked defense.  So I adjusted both wins and losses by separating games where defenses were within three ranks of each other from games where defenses were four or more ranks different:

Now the 55-41 win rate by superior defenses shrinks to 39-28, whereas the record for games between similar defensively powered teams ended up at 16-12.

This result surprised me, since the win percentage for all three of the breakdowns are almost exactly the same:

Apparently the level of difference between the defenses didn’t matter as much as I thought it would.  Regardless of that difference, teams with a superior defense seem to enjoy about a 57% chance of winning in the postseason.  That’s somewhat significant but hardly dominant.

In fact, the only round where the defense seems to make a significant difference is in the divisional round where superior defenses have gone 25-11 over the last nine years, and have had a 69% chance of winning.  The better defense’s chance of winning in any other part of the playoffs?  An even 50%.

It seems clear.  Having the best defense on the field has only mattered for one week a year over the last decade.  The rest of the playoffs seem relatively unaffected by the strength of each team’s defense.

But why does the divisional round seem to favor defenses so much when the rest of the postseason seems utterly unaffected?  To be honest, I’m not sure.  I have some vague ideas, but listing them here would be nothing more than taking shots in the dark.  If you’d like to share your own theories, please feel free to leave a comment.

Homefield Advantage in the NFL

It’s a nebulous topic.  Whether it’s Our House, The 12th Man, or any other name homefield advantage is an intangible that’s often invoked in football.

This season I attempted to use the Power Rank’s neutral site predictive capability and account for home field advantage…  and failed.  I added an arbitrary three points for the home team, a practice that is relatively common when setting a betting line, but a practice that is hardly scientific.

Rather than develop a complex mathematical matrix to divine the true value of the homefield advantage (I’m just not that smart…  I’ll let Ed work on that!) I decided to poke back into the recent history of the NFL to see is homefield advantage is a truly intangible myth or if it is a real and tangible aspect of the game which might one day be quantifiable.

I gathered data from for the years 2002-2010, the only years that represent the current 32 team configuration of the league.

The first thing I wanted to look at was regular season performance.

Since 2002 home teams have won over 57% of the time, while road teams have won only about 43% of the time.  That’s a fairly strong indication that homefield advantage is tangible and meaningful, especially since every year has produced winning records for the home team.  The worst year for home teams since 2002 was 2006, when home teams won barely more than 53% of the time.

There’s a lot that goes into why playing at home is advantageous, from the comfort of your own familiar locker room to the jet lag (or lack thereof) of a coast-to-coast trip to field conditions.  One of the biggest and most obvious advantages is the crowd noise produced by a home team’s fans.  I wondered if this factor would increase the homefield advantage during the playoffs, when fans are going to be louder and more interested in every play of each game.

Here are the results for homefield advantage in the playoffs since 2002, with 2010 incomplete (and not counted):

This time there’s an even stronger correlation between home team and victory in the final win percentage, but the playoffs have special conditions that must be considered before jumping to the conclusion that the correlation is in fact stronger.  First of all, in the regular season the home team is more or less random, whereas in the postseason the home team is determined by the strength of their regular season finish…  usually.

In most cases homefield advantage in the playoffs is awarded to the team with the best record (or by tiebreakers if they had the same record) but this is not always the case.  Division winners are awarded home field advantage over wild card teams regardless of record.  That’s why the 11-5 Saints visited the 7-9 Seahawks, the 10-6 Packers visited the 10-6 Eagles (who they had beat on tiebreakers), the 12-4 Ravens visited the 10-6 Chiefs, and the 11-5 Jets visited the 10-6 Colts last week.

So in the wild card round, you have teams with better records visiting arguably worse teams that won their division.  The results from these four games last week?  A 1-3 record for home teams, with the Seahawks pulling of a somewhat miraculous win over the Saints.

So I also broke down the records of wild card games by homefield:

Not only is this correlation weaker than the homefield advantage in the regular season, its also generally weak.  52.8% versus 47.2% doesn’t create insurmountable odds.  In fact, the odds for an away team to win in the wild card round are about equal to the odds of beating the house on a casino Roulette wheel (with 0 and 00 spaces).

So what happens in the divisional and conference championship rounds when homefield advantage almost always goes to the team with a better record?

Now the correlation is at its strongest, but again the home team is already coming in favored since they usually have a better record, especially in the championship round when the home team always has the better record.

Does this just mean that the better team is winning?  I don’t think so.  The correlations here are significantly larger than the correlation in the regular season, and as all football fans know, the best team doesn’t always show up and win.  I’d attribute the correlation in the later playoff rounds to a combination of the two:  a better team playing at home has a very significantly better chance of winning in the playoffs.

So what does that mean for this week?  All of this week’s match ups feature a weaker team visiting a stronger team.  This is the kind of correlation we see in the conference championship round of the playoffs, about a 69% chance for the home team to win versus 31% for the away team.

Seattle losing to Chicago and New York losing to New England seem like safe bets this week by conventional wisdom, but the other two games are less certain.  Baltimore finished with the same record as Pittsburgh and lost the division on tiebreakers.  The  Power Rank’s #2 team Green Bay visit the Falcons, who needed a few lucky breaks to win at home against the Packers in week 12 this season.

If one of these potential upsets occurs, the record for better teams playing at home this week will be 0.750, close to the expected 0.688 correlation that is shown in the conference championship rounds of the last eight playoffs.

So it seems that homefield advantage is certainly tangible, and is particularly strong when it favors an already superior team (according to record) in the playoffs.

NFL Predictions, Divisional Playoffs

Pittsburgh will beat Baltimore by 2.5 at home

Green Bay will beat Atlanta by 0.0 on the road

Chicago will beat Seattle by 9.9 at home

New England will beat New York Jets by 9.7 at home

The predictions were 4 of 4 against the line for Wild Card Weekend. The lines were taken from USA Today on Friday night.