What would happen if Serena really played Roger
is it really a blowout, or do you guys think it would be a competitive match
It's not even a debate really. Men have a (maybe unfair but natural) physical advantage and even if Serena would beat 99% of male tennis players out there, when pushed to the limit, male athletes will always have a significant edge. So yeah, she would probably lose against a good part of the top 1000 of the ATP. Which, again, is a ridiculously small sample of all the men who play tennis out there, but still.
This McEnroe story really is a non-issue. I mean you can clearly see one side not accepting a clear difference that doesn't erase at all what Serena and other female champions have achieved, and the other eager to explain in every way possible (often with dumb examples, I've seen a youtuber say that he could beat Serena with a few weeks of training, because he was a man and she was a woman. Clearly he hasn't played tennis ever) that men are STROOOONGER, primarily to reassure themselves that it's true. Neutral people, which are the clear majority, just watch tennis and enjoy.
Edit :
The only real cross gender match without point advantages or allegations of match fixing or not playing their most competitive was 1998: Karsten Braasch vs. the Williams sisters
See this Braasch example is typically what irritates me in this "debate". Ok, he was probably smoking and drinking a bit, so what? Some players in the top 100 do too. He played golf before the match? A lot of the guys on the tour play too, and it's not a terribly tiring sport. No need to act like he was out of shape and wasn't even trying. That's a guy who was top 40 in the world at his best and in the top 40 of doubles when he played the Williams'. It wasn't a recreational player, he was really good. That's why it's a significant example of the difference there is. No need to emphasize every detail.