He'll probably look bad in that context but you know, so do most NBA bigs
Jax is a great example actually. Came in this year undersized. Everyone said it should just be a redshirt year, he was at least 2 years away, definitely couldn't be good.
Instead he played about 1000 minutes, and while it was obvious that he has places to improve, and yes his low weight caused him issues, he was actually a lot better than most people thought he would be and showed legitimate improvement throughout the year.
Poku right now, today, is going to be a defensive liability against bigs who have him outweighed by 40lbs. That is absolutely true. But most bigs who are 240lbs will also be defensive liabilities against him, because they can't keep up with someone that has such an advanced handle, such an advanced passing game, and shooting ability. Does that mean I think he's ready to be an NBA starter or whatever right now? Obviously not, but I do think this idea that someone being a few years away from their peak in one respect means they are years away from contributing in the league. Trae Young's still a defensive liability, and probably always will be, but that doesn't stop him from being very good at the NBA level.