Lots of nimble PGs are liabilities in defense, Steve Nash for instance. But Kidd can guard anyone, and even at 40, he showed today that he can guard 1, 2, and 3. He harrassed Paul Pierce, guarded Green from time to time. He was heads-up all the time, bumping the ball handler, playing the passing lane. He was all over the place, and played 35 minutes!
At the time of Kidd signing, Lin was still perceived to stay with Knicks, some of the new fans here were upset that when Kidd said something along the line, that he wouldn't mind playing off the bench, but coming closing time or playoffs, his experience would be needed. This game just shows you how precious such veteran leadership is, especially coming playoff time.