At Sounder at Heart, agkt wrote a very interesting post on the strength and importance of home field advantage in MLS. It explores the home field advantage difference between MLS and other major North American professional sports league and it looks at the average difference between a team's home goal differential and road goal differential.
The entire post is well worth a read, and here I will try to apply agkt's findings and methods to the Philadelphia Union to see if we can find a reason why the Union are succeeding as they are this season. According to agkt, the average MLS team has approximately a difference of 12 goals between their home goal differential and road goal differential.
The closer a team's goal differential difference is to zero, the more equal a team's performance on the road is to their performance at home. Whether it be equally good or equally bad depends on the team, but in a league where home field advantage plays a pivotal role and most teams are significantly better at home than on the road, relatively stronger performances on the road can be the difference between playoffs or no playoffs.
Now if we take a look at the Union, their difference between their home goal differential and road goal differential is eight goals, four smaller than the MLS average, meaning the Union's relative strength tends toward road games. Looking at goal differential, you can see this would make sense. The Union's home goal differential currently stands at +6, good for fifth in the Eastern Conference. On the other hand, the Union's road goal differential is -2, good for second best in the Eastern Conference, behind only Sporting Kansas City, whose +2 road goal differential is the only positive road goal differential in the Eastern Conference.
Seeing as the Union's goal-scoring record has been only mediocre at home when compared to other teams, it can be inferred that a strong reason why the Union are in third place in the Eastern Conference is because they have been better than average on the road.
This is important because the Union's next match is a big one on the road against a New York Red Bulls squad currently in second place in the Eastern Conference. The good news for the Union is they are a relatively strong road team. The bad news? The New York Red Bulls have the second largest gap between home goal differential and road goal differential, indicating the Red Bulls have a wider than average split between home goal differential and road goal differential. Unfortunately for the Union, the explanation is not so much Red Bulls are weak on the road as the Red Bulls are a middle of the pack road goal differential team.
But just how strong are the Red Bulls at home compared to other MLS teams at home? The New York Red Bulls lead the Eastern Conference in home goal differential.
The Union are a formidable road team, make no mistake about it. But they are about to walk into a buzzsaw and recent games at Red Bull Arena have been unkind to the Union. Even as a strong road team, the Union face a real uphill battle Saturday evening.