Reasoning:

Lakers - This trade improves the defense a lot as smart is a previous dpoy, although not as good defensively as he was he’s still great. Offensively he’s not amazing but serviceable.

Wizards - Smart isn’t needed on this team so trading him to let the young guys have more play time is smart. You wouldn’t lose any vet presence as you’d get Vincent and kleber in return. Plus you get some more draft capital for the future.