No.
First of all, Lee is not a medicore defender, he's decent. He's a bad rim protector, decent in the pick and roll and good one on one on the interior. He also has a good 18 footer, contrary to the lack of jump shot claim.
He's by far our best player. A consistent 18-20 point scorer and a great rebounder. Even when he went off the bench in GSW, his per minutes production matches his All Star numbers. He also provides an extra playmaker on the floor with his passing ability and a knack for finding cutters and open guys. Why would you bring that guy off the bench?
Well, last season Kelly Olynyk scored at a better rate per minute with a slightly higher true shooting percentage. Lee had better passing numbers and better rebounding numbers.
Defensively, I'd give the edge to Olynyk, although they have different strengths and weaknesses.
A big plus for Kelly is that he's our only big that has legitimate three point range.
David Lee's career would seem to be on its downward arc, while our young bigs--Sullinger, Olynyk, Zeller--are presumably still on an upward arc.
David Lee might win the starting job, but I think it's far from a sure thing.