it is the way it is, you just use the wrong example.
It's the same as Federer and Rafa, they're equalish despite the actual overall H2H, that's the whole point, it's not made on purpose to serve one or the other.
If Fed loses from Ferrer on grass, i would be the first to say he's not his pigeon anymore..
But these aside, it takes more than one match for one to be considered favorite of winning comfortably on this or that surface.
And i think that's the idea of Litotes - if the H2H per this surface is such as having the player with more wins as big favorite, then owning is achieved.
Ferrer would need to beat Federer 3 times at least on grass to rate him favorite on their 4th meeting, so i believe the system is (almost) perfect
I say almost, coz we'll need to implement a numerical denominator, coz "expected" is not exactly a perfect term for making a rule.
I believe we could put some combined bookies' odds to somehow "prove" the "expected" part and we can put it in writing
Yes, I am a little surprised to see it described as a "system", but my general thought was this. You have a matchup. For example, Federer against Ferrer. For their next match, who is favourite? Federer is. Now, for Federer and Nadal you ask she same question, who is favourite, the answer will not be an immediate "Nadal", it will be "Where are they playing?". If the H2H is such as to make the question of where they are playing less interesting, that is owning imo.