Seriously, there is not going to be a huge influx of people for this game. The Pro Bowl is a non-entity on the current sports landscape. Moving it to Orlando is a last-ditch effort by the NFL to save it.
Most players who are selected for the game back out, and you end up with the fourth-best or fifth-best players playing each position. It's not an event fans travel to. It'll attract locals to the actual game, but that won't affect the park crowds. And most of the players and their families won't stick around to hit up the parks beyond the official MK appearance, they will all head for the Super Bowl site as soon as they possibly can.
If you have a trip around this time, take a deep breath, you'll be absolutely fine.