Sheldon Williams! Really??

So the Celtics are about to sign power forward Sheldon Williams for 1.3 mil guaranteed which makes me wonder what the f#@k are they thinking. Here is a guy that will give you nothing on the offensive side of the court, and when I mean nothing I am talking to the tune of 4.7 ppg for his NBA career. He is an average one on one defender a decent team defender and little above average rebounder. Any of that sound like 1.3 million to you? Because to me it sounds like Marty Collins.