That's not to say that stats have rendered the 'eye-test' obsolete in baseball, far from it, every sport still has that human element regardless of how deep the stats go...nor does the cumbersome nature of devising good statistical models in tennis make such an endeavour worthless but...**** it you're intelligent enough to fill in the blanks, and I'm tired a.f. from a long work week.
First of all, people are either going to understand what you are saying - and I do - or they aren't going to understand any of it. So when you make intelligent points, be prepared to be understood by other intelligent people, and be content with that.
I think the biggest variable in tennis is the lack of a control.
If you are thinking about bowling - and by the way I know next to nothing about it - I would assume you can rate players against the simple fact that 300 is a perfect score, and you can't better that. So if player A wins a tournament with less points than player B gets in another tournament, who loses, we can at least guess that the competition at one event is higher.
If it's straight pool, we can look at consecutive balls pocketed. We have to make sure that when comparing we are talking about pool tables that are the same size, with pockets that are the same width and shape, but other than that I don't expect things to change too much.
But in tennis the only thing we could theoretically compare would be the serve - the speed of the serve, the amount of spin, but then we are hit with the problem of equipment.
At least in baseball it pretty comes down to what a pitcher does with the ball he throws. (Baseball experts may think of something I'm missing.
For a marathon I suppose maybe better shoes make a difference, and I don't know what other factors are there, but doesn't it pretty much come down to how little time you complete the marathon in?
So if you want to argue about how much better today's athletes are in the marathon, you can simply look at the records and how the time has come down.
But what do we have in tennis?
We have comparisons between Laver, with a wood racket, and Federer, with completely different equipment. Everything is different. And yet people still use the "eye test" to make claims about who is better, and why.
Even right now there are arguments about the playing level in any given year, saying that peak Fed had easy competition, or Nadal's USO last year was next to worthless because of such an easy draw, or that somehow Novak's non-calendar-year GS only happened because competition was getting weaker. And all these conclusions are based on "eye tests".
So no matter how problematical tennis stats are - and there are indeed HUGE problems - I think they are at least a help in combating stubborn adherence to the eye-test, which claims to be more accurate than any set of facts.