Thank you all! I was gratified to see all the varied responses. The points about processing speed and emotional intensity were very interesting as were those regarding introversion and extroversion.
With DS8 (HG+), I think it's twofold. He's kind of asynchronistic in his personal interactions and also gets overstimulated by experiences outside the normal everyday stuff. So going to basketball or baseball practices and games overstimulated him to the points where he's in everyone's face and trying to play tag with these older boys who are there to win. He just doesn't know what's appropriate for those interactions. Interestingly, he is fine with his normal school friends who are generally of the same ilk as he. So an overstimulated extrovert at practice equals no focus.
Also though (threefold perhaps), he does have a relatively low processing speed. So perhaps it is difficult for him to think quickly out on the court/field and he just appears to be spacing out. He's one of the kids who doesn't know where the play is or doesn't know where to stand to be in position for a rebound. He basically looks like he's watching sometimes. So certainly his sports IQ is not high.
I did find out something interesting which shows how our memories are sometimes what we make them. I was talking to my mom about my childhood. I was GT but likely only MG. She said I didn't really like to play team sports like basketball and baseball but did it because my friends did. She said I really came into my own when I took up competitive swimming because I could hang with my pals and still compete. I, too, had low processing speed (the Socratic method in law school left me tongue-tied often).
Conversely, DH was a high achiever who is VERY quick on his feet and excelled at hoops, football, soccer, and baseball.
Either way, DS has made dramatic improvements out on the court/field. He's great at handball at school. Loves that. Loves hitting the tennis ball around so I think we will let him try some tennis next time. I just wish he wouldn't be so goofy out there but I guess that comes with the territory. He's also VERY skinny and not that strong so I should be grateful he can make a shot on a 10 foot hoop.
DD5 is way more savvy than him, totally focused and competitive. It's kind of funny really. She just took the kinder GT test, we will see.
Thank you so much everyone! The insight is so very valuable, I can't begin to tell you how grateful I am.