NFL jersey sales aren't the be-all and end-all.
But the numbers do speak to the popularity of players and fan bases.
Which leads us to this poll in which former Eagles quarterback Donovan McNabb's Redskins jersey was the second-most popular in the month of April.
The guy who was more popular wasn't Kevin Kolb, although he emerged on the following list:

http://nbcsports.msnbc.com/id/36969513/