I like it
No matter what he'll add to the team (and I think he adds a lot, he can rebound, which is more than we can say about KO or even Zeller...) it's a bigger expiring contract (that we can afford without going into luxury tax), so a better trading chip down the line. There has to be another contract there, I'm sure it'll be Pressey's.
For GSW it saves them money, either by paying Wallace less than they would have payed Lee (that's what Spears is reporting), stretching him or trading him for an even smaller contract (7 M, let's say) to save even more.
Lee still has game. He's kind of like Sully, with less future but better present.
And that's one of the reasons I think Sully will be out before the season starts. Next year he'll be up for a new contract (with a qualifying offer) and I suppose front office is on the fence about paying big money.
Right now he has value as a trading chip (unfortunately not as much as we could have gotten if he hadn't got injured, but still... - and in that area DA has been really unlucky - the Rondo trade was put off for a year, with a smaller return, because of his ACL tear) and it's time to cash in. Probably to find a good foward, if there is one - I've seen people here mentioning Chandler, I think that could be an option, but I'm sure there are others.
Even if Sully isn't moved right away, consider this:
Thomas-Bradley-Crowder-Lee-Amir
Smart-Rozier-Turner-Sully-Olynik
Plus Jerebko and Zeller trying to get minutes
And Hunter, Young and Mickey getting reps in the D-League.
For me it's a play-off team. The starting five mightn't be, but it's the best depth in the East, and noone can play the starting five 40 minutes a game, at least during the regular season.