I think he might mean things like:
Nationals: Nats
Rockies: Rox
Orioles: O's
Redskins: Skins
Alex Rodriguez: A-Rod
Michael Vick: Bong Carrying Ron Mexico
A Cheater: Barry Bonds
NOOOOOO. I MEAN LIKE NATIONALS INSTEAD OF WASHINGTON
ORIOLES STEAD OF BALTIMORE, ETC. ETC.
I agree with you that the sports journos presume much more a priori knowledge than the other hacks, but don't you think that's probably justified given the nature of the readership? Only hockey fans know who the "Habs" or the "Bees" are, and similarly, only soccer fans know who the "Hoops" or the "Hibs" are. Baseball is the same way.