You can try to make an assumption based on record for online purposes and get somewht slight results.
For instance:
Anytime I see someone with equal losses to wins or more losses than wins in Ranked. I pick my side characters or characters I'm "ok" with because I'm confident I don't need my main. And I'm usually 99% right.
Now when it comes to wins vs losses.
Ranked: if they got 2 wins per loss, I can usually get away with playing my 3rd string character (3rd best)
3 wins per 1 loss(or better). I usually go straight for my main. They will normally give me a pretty decent challenge, if not sometimes beat me.
When it comes to PLAYER match matches... They don't mean crap.
You don't choose your opponents in ranked. but you can choose them in player match, and that's why it will never mean anything. My record is like 1090/731 I generally play people of equal skill or greater, but I do run into noobs sometimes. I don't decline invites if someone worse than me wants a match. So I give them 1 set. 2 matches or 3 if they can take one off me. If they beat me I will play them as much as they want because I want to learn.
I fought a cyrax with more losses than wins. And he raped the shit out of me. Why did he have more losses than wins? because he's in a clan and he always plays the same 5 guys over and over and they are all better than him.