I think Brandon Ingram needs to gain some weight (just like every other person that's ever seen a picture of him) but he's only 18 so I have no worries that it'll happen. I also don't think I care much.
George Gervin was skinny and he had a pretty decent career. Reggie Miller was skinny and he wound up OK. Kevin Durant is still pretty skinny and had a great bounce-back season this year. Kareem and KG are guys who played different positions but they were both skinny and it didn't seem to bother them.
It seems like Ingram's weight is one of the first couple of things I hear when I hear people talk about him but there's a pretty good history of skinny NBA players having success.
I'm not that familiar with Gervin's frame/game, but i don't think the competition wa as physical then as it is now.
KG and Reggie were both quite tough physical despite their skinny frames - Ingram comes across a bit soft in personality by comparison.
KG was also an elite athlete. Ingram is a pretty good athlete, but not an elite one.
Kareem was 7'2" so he and KG were able to use their elite length and impressive post skills to shoot over guys in the post. Ingram at 6'9/6'10" with a 7'3" wingspan has elite length for the SF spot, but not for the PF / C spots (where great length is arguably most beneficial).
Id say the closest comparisons in terms of body type would be Giannis and Durant, but i think both guys have superior athleticism, and Durant's level of talent im college was on a whole other level.
Honestly i am a bit concerned by Ingram's frame. Of course hes young and has lots of time to bulk up, but if he doesn't it could limit him.
I don't feel i gram has the size to dominate the PF spot or the athleticism to dominate the SF spot, and i question his toughness. I've got some real uncertainty as to whether he'll become the future star people predict him to be.
Personally, i feel Simmon's upside is on a whole other level. He has similar attitude question marks, but he already has an NBA body and game, so he doesn't habe aa much to work on. All Simmons needs is a half decent jump shot, and hed probably become a top 5 player.
Ingram On the other hand might become a Giannis level player - still good, just not transcendent.