Each season, the PGA Tour does several re-shuffles of the guys who are in exemption priority category 24 - the guys who either got their season card by getting through Q-school or finishing 2-25 on the Nationwide Tour.  (The #1 guy from '09, Michael Sim, is in his own category ahead of these guys.)

The re-shuffles do just that: change the order in which guys in this category qualify for open fields on Tour.  So, the winner of Q-school and the second guy on the Nationwide Tour get to start the season ahead of the others, and they go in alternating order.

After the first re-shuffle (and each subsequent one), the priority order changes based upon the money that each of the players earn to that point in the season.  Their performance determines the maximum number of fields they can get in simply based upon room.  Start poor and a player will likely end the season poor, and back in Q-school.

The first re-shuffle happened after the Waste Management Phoenix Open and will apply until the next re-shuffle after Houston.  As you might guess, Rickie Fowler and Alex Prugh lead the re-shuffle.  Fowler nearly won in Phoenix and Alex Prugh played very well in California.  Naturally, they're in great position for the next month.  Of course, Fowler backs that up with a MC at Honda, but what can you do?