The number of Red Sox fans that keep bringing up 2004 is astonishing and frankly laughable. I heard someone say that the 2009 World Series didn't count because the Yankees didn't have to go through the Red Sox. OMG! You once won a postseason series against the Yankees!! That means you're so much better than they are and will be for the rest of time!!!!!
Above all, this is pretty much what I found, judging by the comments on the internets.
Red Sox fan bragging about a sweep of the Yankees and first place in the division in April: totally okay.
Yankee fan bragging about a sweep of the Red Sox and first place of the division in August: YOU'RE COUNTING YOUR CHICKENS BEFORE THEY HATCH MORON!!!! REMEMBER 2004!!!!
