This article is so deadly accurate I want to quote the whole thing. Instead I'll just stick to the names of each category of "that guy in your league" and let you read the descriptions for yourself:

Mr. Add & Drop
Mr. Disappearing Drafter
Mr. 2001 All-Star Team
Mr. 2010 All-Star Team

Quoted: Mr. Hometown Hero - This one seems to involve Yankee fans an awful lot of the time. You can tell who this person's favorite team is by looking at his roster for two seconds. It is loaded with players from one specific team, and the holes are filled by guys who USED to play for that team.

For what its worth, I am probably a combination of Mr. Add/Drop and Mr. 2010. Last year I had a dash of Hometown Hero as well, but the Tigers offense was sick and I had its two best players.