I was browsing ESPN.com today, and I linked myself to the 'Daily Dime', which basically reviews the previous day in basketball. Then it said for Dec. 4, Marvin Williams was the best player of the day. Then I clicked 'See how all 121 players stacked up'. I noticed Pierce was first, so I decided to click Season Leaders.
According to these ESPN Efficency rankings, Pierce has been the 2nd best player in the NBA this season, behind AI. Kind of surprising.