I agree with you on this one. And it is probably a reflection of the fact that too many fans like to just blindly quote a player's stats rather than really looking into them.
I look at a couple for things regarding Ryan. First off, I look at the fact that he never won a Cy Young. As a matter of fact, he only finished in the top 10 in Cy Young voting 8 times over his 27 year career. So for about 70% of his seasons people didn't think he was even one of the top 10 pitchers in the league. He also was only selected for the All Star game 8 times in those 27 seasons.
Some will argue that he played on bad teams. But the teams that he played for finished well above .500 in the seasons he pitched for them.
I will agree - 7 no hitters is an unbelievable feat - especially when you consider only one other pitcher had more than 3 in a career. But a lot of his other gaudy stats are really more a reflection of the length of his career rather than being a true all time great.
I will disagree on one of your points. I actually analyzed his winning percentage against that of his team and it was slightly better. But it wasn't a real big difference. And you are right - he very seldom was even the best pitcher on the team. I think he led his team in wins only 3 or 4 times.
When he was on, he was incredibly good. As a matter of fact, he was unhittable at times.(obviously)
But when he was off - he was really off.
Definitely deserving of the HOF, not in the top ten.