From the NBA press release:
For the first time, the NBA All-Star Ballot presented by Sprint will feature two position choices, guards and frontcourt, NBA Executive Vice President, Basketball Operations Stu Jackson announced today.
Fans will select two guards and three frontcourt players when choosing the starters for the 2013 NBA All-Star Game. Previously, the ballot featured three positions with fans picking two guards, two forwards and a center.
"The NBA's competition committee and the league office agreed that having the center position as the only specific position singled out on the ballot was outdated and not representative of today's game or players," Jackson said. "Our players have become more versatile each season, and this ballot will more accurately reflect that versatility."
The 2013 NBA All-Star Ballot presented by Sprint will be unveiled on Tuesday, Nov. 13 during a special event in Houston.