Are sports winners more violent than sports losers?

The [research] team focused on the 106 international rugby or soccer matches between 1995 and 2002. On non-match days, the number of assault victims averaged 21 per day, and on match days when Wales lost this rose to 25. But the situation was worse after a win, with 33 admissions per day on average…

Match days would seem to organize groups of rowdies, if nothing else; winning might embolden their violence.  And don’t forget about alcohol.  Read more here.  Here is a related account.

Addendum: Thomas Edwards points to this explanation.