Return to Strength of Victory

» Posted by Vince on August 25, 2008«

We noted that margin of victory is a poor indicator of strength of victory. The problem is that a late score in a game can make the it seem closer (or not as close) as it really was. GridIronMine calculated the strength of victory of all games using its Victory Forecast.

The above graph plots the final point differential--the margin of victory--against the average VF for the game--the strength of victory. The margin of victory ranges from 1 to a maximum of 46 points (New England over Buffalo). On the other hand, strength of victory ranges from 25.1% average VF (Dallas over Detroit) to 92.6% (New England over Buffalo). While the plot shows that there is a general trend the correlation not high. For example, consider that Cleveland beat visiting Baltimore by 14 and KC also won at San Diego by 14. Cleveland lead by at least two touchdowns for more than 50 minutes, and by 21 before giving up a meaningless touchdown (that increased the Raven's VF from 4% to 6%) in the fourth quarter. In contrast, the Chiefs led for only 12 minutes (and trailed for 34 minutes), but it was the last 12 minutes while scoring the last 24 points of the game. While point differential considers both games equivalent, strength of victory grades Cleveland at 90% and KC at 39%.

The above analysis does not consider the quality of opponent. San Diego was one of the top teams, so KC's performance should be consider better than the same performance against an average (or below average) team. Similarly, Baltimore was below average, so Cleveland should be given less credit for its performance. This leads us to create opponent adjusted strength of victory measure. The tables below that show this for the 2007 regular season. The left side is ordered by SoV, the right side by change in rank.

There is little surprise that the top team is New England. The first surprise is that Washington comes in at number 5. That rank is 7 positions higher than their rank by win-loss percentage. The reason is that Washington was competitive in most of their 7 losses, having second-half leads in 5 of them. Additionally, the Redskins had a 6 wins that were better than average. The team with the largest increase from rank by win percentage to rank by SoV is Chicago, 8 positions from 18 to 10. The argument can be made that these teams are better than their records indicate.

On the other side of the coin, San Francisco edges out Miami for last place. Nine of the 49ers 11 losses were below average, 4 were romps, while all 5 wins were below average. There are several teams that have much better win-loss ranking than SoV ranking. Cleveland has the 7th best win percentage, but ranks 19th in SoV--a whopping 12 positions lower. While the Browns had 10 wins, 2 of their 3 quality wins were against the bottom two SoV-ranked teams: San Francisco and Miami. They were blown out in 2 games. Moreover, they played only one team in the top third of SoV, while 6 games and 5 victories were against bottom-third teams. Carolina and Arizona also had double digit differences in SoV and win-percentage rankings. The argument can be made the these teams are not as good as their records indicate.