Spring Training is a time for players of all levels in a teams system to get a shot. 99% of the time, they're headed back to the minor leagues after their spot duty, but the broadcast crew will try to regognize their story and accentuate the positive.
Unless you're #91 on the St. Louis Cardinals. Check out this gem from friend of the site Matt Sebek:
Tremendous, FSN. Fantastic, really.
As Matt suggested, I'm already looking for my #91 custom "Minor League Guy" shirsey.
UPDATE: "Minor League Guy" has been identified: LINK HERE