He's not scum. He's just no longer good at his job. Go back a decade and Davidson was good. He has held on far too long.
One more point on Joe West, prior to the 2011 playoffs, he had Angel Hernandez on his crew for several years. Last year and in 2013 he has Andy Fletcher, who is quite good and in his mid 40s, along with Rob Drake and Sam Holbrook, who are both darn good as well. It's amazing what happens when your crew mates are good!