He's good. Wouldnt want him in Boston though because he would disrupt team chemistry.
I would rather go for Parker who's been riding the pine since the season started. Like Oubre, he has almost similar size but with more muscle. He's still young, athletic, good shooter, with decent post moves and some other intangibles.
Parker is on his 5th team in 7 years, been so injury prone he has played in just 285 games out of 500 he was eligible to play in and currently is so good and healthy that he hasn't played a single minute for the less than good Kings.
Sorry, for me that would be a hard pass. If the Celtics are trading for a wing it should be someone that can shoot threes, play some defense and not be a ball stopper, all things Parker isn't.
But, looking at things differently, picking up reclamation projects on the cheap and having Stevens coach them up to play much better is definitely something Ainge does. So Ainge picking up Jabari Parker on the cheap, could be a good call by you.