Pity poor Paul Allen. He only came in at No. 20 on the Forbes list of the 400 Richest Americans. But at least he’ll have something to hold over the heads of the other owners when they convene next month for the Board of Governors meeting in New York (then again, Allen– worth 15 billion– may not attend. He usually sends someone in his place). The only owner who can flex muscles with him is Mikhail Prokhorov of the Brooklyn Nets, with $13.2