Chibo, the concept of "rankings matches" is dumb (no offense), so let's cut that idea right now. With mms, once you're out of money, you're out of money. Basically what Smurf said.
- With "serious rankings matches," John could challenge Squall 50 times and lose 50 times, and at the end of it, the only thing proven is that Squall is better than John. Oh well.
- With mms, if John mms Squall even a few times and loses, he's out of a good bit of money and won't keep playing unless he's REALLY **** SURE he can beat Squall. He's gonna play his best, because there's increased risk for losing, and Squall's gonna wanna keep that money.
As for your problem with putting a value on mms compared to tourney, that's what the panel already does in a dozen situations. Wins vs. losses. Mains vs. secondaries. Earlier wins vs. more recent ones between two people who've played each other multiple times.
If it was a simple mathematical equation, we'd put it into a computer and get a nice little list to pop out..... but it's not. You're trying to skip out on doing what the panel is supposed to do: make objective decisions with subjective data, which is what any PR list is.