20131. Dwight Howard, Rockets center
Age: 27. 
Last year: Not on list.Why he matters:The franchise’s long history of cornerstone big men gives the Howard signing extra significance. It’s the biggest deal of the off-season in the NBA and, for the Rockets, it’s exponentially bigger than last year’s acquisitions of Jeremy Lin and James Harden if Howard’s that missing piece they’ve been seeking for approaching two decades. With Howard on patrol down low, they’re an A-list franchise again.Defining moment:The dunk contest Superman outfit was a marketing coup, but muscling the Magic into the NBA Finals in 2009 established his bonafides.Staying power:He’s contractually bound to be here for three seasons with his option for a fourth so, if he stays as happy as he seemed to be last weekend, he should become a civic treasure. Photo: Karen Warren, Chronicle