Standards for proof are two-sided, involving reliability and validity. Stats are reliable because everyone agrees what the numbers mean, but you bring up a fair point that the numbers may not be a valid reflection of reality. "A nose for the ball" is a valid trait in regards to rebounding, but how do you reliably make comparisons between people?
Here's an example of how murky your "provable" becomes. You could constrain rebounding numbers to apply to major conferences only. OK, but Harry from DePaul better. You could observe, correctly, that overall Stanford is a better rebounding team hence Ogwumike has better competition from her own teammates. OK, but Maryland is an even better rebounding team, and I'm telling you that Hawkins girl seems to have quite the "nose for the ball." Put Ogwumike in with the same "competition" Hawkins plays with every game to get rebounds and her numbers won't be as good. Her recent average jumped because of outliers. Hawkins could not possibly get such outlier numbers because teammates like the All-American Thomas are just too good at also getting rebounds.
But what matters here is that you think the match-up of Faris on Ogwumike works to Stanford's advantage. You actually have company in the UConn camp. Auriemma said that while Faris can guard anybody, if she is on Ogwumike the whole time he is worried about what Stanford might do with our bigs out on the perimeter. Faris will likely guard Ogwumike most of the time, but not all the time because of this concern.
That's different than the one reason you provided for liking the match up, Ogwumike being (allegedly) the best rebounder in the country. Even if we concede Ogwumike is the best rebounder in the country, she gets a lot of offensive rebounds. Put a supremely athletic and strong "box out" person against a supremely athletic and strong "nose for the ball" person and the "box out" person wins most those matches. Depending on how hot she is Ogwumike might still score well on Faris (though it's amazing how many All-Americans seem to have poor shooting games with Faris guarding them) but her offensive rebounding will not be as effective if a strong, athletic defensive master is determined to stay with her and stop that.
The trouble is that a person really focused on "boxing out" seldom gets a rebound as well, the ball has to come to her. If this goes on with our bigs out on the perimeter this could still work to Stanford's advantage if your coach makes the right moves, which she often does. In turn Auriemma said he will have to be smart about matching Faris up with Ogwumike, and he no doubt will be. That's why Stanford/UConn should always be a fun game to watch, though both teams are much more physical than either coach wants the referees to believe about their own team.