Eh, the answer isn't as clear cut as some make it out to be, but you'd still probably have to do it if you believe in what Winslow can become.
Sure you'd have to kinda change directions in a sense, but that's part of the beauty of how Ainge has set up this rebuild. It's all about flexibility.
If we were to finish the season disappointingly, we have the ability to change gears and go very young pretty much whenever we want. Lee will be gone in a month anyways, Jerebko and Amir both have non-guaranteed deals next season, Sully and Zeller are RFA, and the only other guys we have that aren't on rookie deals are Crowder, Thomas and Bradley. And those guys have three of the best contracts in the league. Easily trade able for good returns. We could easily go for a total youth movement if need be and have to do very little maneuvering to get it done.
That's always been one of the plans, I just can't see us disappointing to that degree. This team is on track to win 47-51 games and make a top 4 seed in the East as the 5th youngest team in the league while receiving a top 5 pick in the draft. Unless a deal you literally CAN NOT pass up (A Winslow for Crowder swap doesn't quite fit that bill for me), I can't see us going that direction right now.