Left out 16 year old boy in middle school

I'm the father of a 13 year old daughter who has a 16 year old boyfriend in her class in middle school and I feel for the boy. He came to her school in the middle of last semester and doesn't have any friends in the class and isn't allowed to participate in sports due to being already 16. We live in a small town and there's not much else to do here. Every week I watch my daughter's sports games and every game he comes along to watch. I think I've gotten close to him by talking to him while we watch these games and I keep thinking if there is anything I can do for him because his life doesn't seem great.

So he's 16 and in middle school and it's not fun for him. His dad passed when he was young, his mother met a new man with whom she had 2 younger daughters. The mother and man separated and those 2 daughters now live with the dad and only visit during some weekends and holidays. Son lives alone with mother who works a lot and is constantly stressed out about work. For some reason I'm not clear on she didn't enroll him in school until a year later than normal when he was young, and due to them moving several times in the middle of semesters he's not had the opportunity to finish middle school and didn't have the option to start high school right away when they moved here. The boy is bright and in my opinion rather belongs in a gifted program than in middle school. I've asked him how he feels about being in middle school and his response has been "it's better than the alternative" by which he means it's better than dropping out and regretting he doesn't have any education at 25.

Since he is older than the other kids, and on top of that what I'd call mature for his age, he isn't connecting with the other kids. He says he feels more like he's watching them growing up rather than being part of it and growing up with them. He says he wishes he was in class with kids his age and going through the same stages of life together with them. In my opinion he is significantly more mature than any of the other boys in my daughter's class. I thoroughly enjoy my conversations with him during the games and consider him great company, and I understand he's not thrilled by spending time with 13 year olds. He's also at a point in life where he needs more freedom than they have.

He used to play sports at some of his old schools, but missed a few seasons due to moving and now he is too old to be part of the teams, but he used to be a really good player. I've seen him playing with a ball while watching daughter's games and one time a middle school guy even came up saying he should play on their team (to which he replied he's too old and can't). He says it's a bit painful for him to watch my daughter play because he wishes he could be playing too, but such is life and it's better than staying home. He tried an intramural league in town when they moved here and played a bit with guys in their 20s, but they were a tight group of friends who had known each other since high school and he didn't feel he quite fit in socially, and eventually stopped playing with them. As far as I know he doesn't have any other social hobbies.

Next year he will be starting high school but he doesn't think he will be picked for those teams either considering he has missed a couple of seasons and the coaches will likely want to recruit freshmen who will be eligible to play in their junior and senior years as well.

In this whole ordeal his mom seems fairly passive, or perhaps stressed out by her new job which requires her to do things she's had no training doing. Son describes her as very optimistic, telling him it's no big deal he is a few years behind other kids in life, that it doesn't matter if you graduated high school a few years later in the end. She doesn't understand his issues connecting to the other kids, according to son she just brushes it off saying there's more to connect over than age, they're in the same classes, have the same teachers, go to the same school, etc. I suggested he might meet older kids once they start high school and make friends there, but son doesn't seem so optimistic. He says it takes time to make friends, if he starts making friends with juniors they will graduate and leave by the time they've become close, and that it's not easy making friends with them in the first place since he will be in freshmen classes and not be invited to any dances or other junior events. Plus they have probably already formed bonds considering they have been in class together for a few years already by that time.

This summer his only plans are going on a week-long vacation to Disney World with his mother and 2 sisters. This vacation is obviously catered towards the 2 younger sisters and he doesn't seem excited about it.

The boy is such a nice kid, very polite and respectful. He's fun to talk to, charismatic, smart and treats my daughter better than I could ever hope for. He's painfully aware of him being a "loser" and very humble about himself, even self-deprecating. We had him over a few weeks ago during a family gathering and he met our relatives. An aunt asked him how old he is and then asked him the natural follow-up question if he is a junior (in high school) to which he replied he is still in middle school, explaining he moved a bit and fell behind. Next relative asks him similar question and once again he has to explain/ excuse himself. I can tell it's not fun for him having to meet new people and explain this, probably aware what assumptions people are making about him.

I guess I just feel this kid got an unfair situation and I can't think of anything to do to improve it at this point. He's never caused any trouble in school, has good grades, and still he's put in this situation. He never gets to shine. My daughter has excellent grades and is a valuable player on her sports teams, which she gets a lot of attention and praise for. He's always on the sideline. While my daughter doesn't have many close friends (she was always mature for her age and didn't connect that well with classmates) she still sees her fellow team players for sleepovers and so on. She has other things to do besides seeing her boyfriend, while he really doesn't have anything other than her (and he realizes this and has expressed to me that he doesn't understand why she is going out with him, only half-joking).

I don't know if there is anything I can do about his situation. I love having him around, value my "friendship" with him and wouldn't wish for any other guy for my daughter, but I can tell he's not quite happy, not quite where he wants to be. Do any of you have any ideas if there is anything I can do to help him?