I don’t particularly believe in momentum in sports, but I did want to take a look at how teams in the NFL changed this year. I decided to take a first crack by plotting each team’s power ranking (explained here) for the season. The team order in the graph is the order from the first power ranking, which came after week 2.
That’s pretty busy, but you can see a few things. First, the much-discussed Chargers were at the top of the league for a good part of the season. They played like champs but it didn’t convert into wins. Second, the Panthers were awful. They’re about as far away from the Cardinals (the second worst team) as the Cardinals are away from the bottom of the rest of the pack. Third, things squeeze together as the season progresses. That means it’s probably a good idea to do a little regressing-to-the-mean earlier in the season, as Brian Burke is wont to do. In fact, the standard deviation shrinks from about .6 in week 3 to about .4 in week 18 (meaning after the last game of the regular season). The mean also moves around a bit because each week adds new data to the model, changing it a little bit.
The rankings are cumulative; they work on a team’s average performance. So the numbers at the right end of the graph should be considered the measure of a team’s quality over the course of the entire season. But we can ask which teams were most or least consistent; who saw their rankings change a little or a lot? For this I looked at the standard deviation of each team’s ranking across the season. The top five most consistent teams were the Colts, Redskins, Panthers, Chargers, and Cowboys. I think the Cowboys are the most interesting case in that group; they started very slowly, lost Tony Romo, and then made a run later in the year. At least that’s what their record says; their play on the field says that they performed pretty evenly. The top five least consistent teams were the Raiders, Seahawks, Saints, Bills, and Jaguars. The Raiders went on a rollercoaster ride this year, starting very poorly then giving out some real beatings before settling into average territory. The Seahawks started out well and then just got bad; the Saints were the opposite. For fun, here’s the same graph as above but with just those ten teams (ignore the labels on the y axis).
Finally, for those of you who do believe in momentum, here are the eight playoff teams. Remember that the rankings are cumulative, so you’d be most interested in who was trending upward at the end of the season as opposed to who had the best ranking in the end.
No one is really trending up, at least to my eyeballs. We could ask who’s trending down; looks like the Seahawks, Bears, Saints, Chiefs, Jets, and Steelers went in the wrong direction. If I only look at the last seven weeks of the season, every team had a (numerical) downward trend except for the Patriots, but the worst of the bunch was actually the Jets, followed by the Chiefs. Of the playoff teams, the rest of the order is Packers, Saints, Steelers, Bears, Ravens, Seahawks, Falcons, Eagles, Colts. So if you think the Jets and Packers are teams of destiny, you can decide if that overwhelms momentum ’cause they don’t have it.
Remember to check in on Sunday afternoon for the Conference Championship predictions!