A lot of people prefer goal differential to points as a method of evaluating the overall quality of a team. I do too, but there are a couple other ways of looking at it. I've gotten a little carried away in some new statistical analysis of the season recently, but I'd like to share some of the basis behind it.

The first few columns show the final league table as we all know it. MG represents "Marginal Goals" - more on this a bit later. Next is Real Win %. This is each team's W-D-L record represented as a percentage. For this, a draw counts as half of a win. Pythagorean Win % is the results of a simple formula used to predict how many games a team should have won:

Pythagoras didn't really have anything to do with this, but the name comes from the formula's resemblence to his theorem.

Bill James (who else?) applied this to baseball originally, and later took it a step further while developing his Win Shares statistic, which quantifies individual player contributiion to his team's record. This is where MG comes into play. Marginal Goals is the sum of a team's goal differential and the league average goals scored. In 2007/08, this was just over 50 goals. If we divide MG by 2 times the league average goals, we get another predicted winning percentage. This one generally isn't quite as accurate as the Pythagorean method, but it generally does a good job for teams who win between 30% and 70% of their games. More importantly, it gives us something to break down further and evaulate individual performance.

A "marginal" team can be described as a team of players at the lowest level of quality in the league. Think of players who would do well in the Championship, but would be lucky to make it off the bench for an average Premiership team. Sunderland of 05/06, who finished that season only 4 goals better than a marginal team, is the best example in recent memory. For most teams, 2-3 goals scored or prevented will earn another win. This season, Fulham averaged 2.007 MG per win, so every two goals we scored/prevented above that line in the sand we call "marginal" would have earned us an additional win. Manchester United, who had plenty of wins already, would need 3.6 more goals to win one more game. Derby County's negative total shows that they really didn't belong at this level, something most of us knew. Fulham, Newcastle, and all other teams who gave up points to them at any point in the season must have really been off on those days.

Right now, none of this (at least on its own) means much. The Pythagorean formula is nice to tell us where we should have been on the table, and it works for predicting future performance. Marginal Goals tell us how much better we are than a very bad, non-existent team. The real good stuff is when we use this to determine individual player value.