A few problems with your example:
1. We're not talking about all kids who play sports or even all blacks kids who play football. We're talking primarily about all black kids who ultimately play in the NFL and become quarterbacks. We're trying to analyze why black quarterbacks aren't pocket passers like many white quarterbacks.
2. You picked a poor example to argue "every situation is different." With respect to
this issue, you either have ... fathers who spend time with their sons helping them to develop their athletic skills (in particular quarterbacking skills) and those who didn't. Situations are going to fall into one category or the other, eliminating the "every situation is different" mantra.
3. I'm glad you prefaced your statement of me generalizing and stereotyping with "In My (Your) Opinion," because the facts which I use to draw a conclusion support my contention, not yours. According to statistics nearly 70 percent of black children are born out out wedlock and more than 58 percent of black children are raised by a single parent, mostly mothers. If more than half of our population are raised without the guidance of a male, I hardly think my observation is a stereotype. And I haven't even factor the dramatic increase of those percentages when we talk about black boys who play sports and those who go on to play on the college and pro level. Furthermore, single-parent families are more likely to be poor and raise poor children and have children who are more likely to get into trouble. Sports has traditionally been viewed as an avenue out of poverty and out of the streets. So when I say that many black families see sports as a way to keep their kids out of trouble, considering that most of our families are headed by single parents, I'm not far off the mark - your personal example notwithstanding.
4. You probably don't realize it, but you've just made an argument for every racists who thinks blacks don't have the mental capacity to be quarterback.
Think about it. You're basically saying that it's more normal for black boys to have fathers helping them and guiding them in sports. (This is the only conclusion I can draw by your statements that I'm generalizing and stereotyping.) If this is so, then how would you explain why blacks aren't generally viewed as pocket passers? One could conclude (erroneously I would say but nevertheless without a thorough evaluation of social dynamics which play a part in this discussion) that black athletes "Just don't get" the quarterbacking condition.
But it's deeper than that. It's a social issue that goes beyond mere athletics. And as I've pointed out, it has to do with the coaching black kids receive as well as the presence of a father (and a father involved in athletics) that plays a huge role in this discussion.
In summary, I doubt very seriously I'm stereotyping or generalizing "too much." All you've given me is ancedotes with no connection to the broader picture. I'll entertain a response fitting your personal example into a larger context.