Um, either you aren't getting what's being said here, or you are being intentionally oblivious. An offshore schools whole reason to exist is to make money off people who have no other avenues to a US med school. They maximize profits by accepting hundreds more people than they realistically could accommodate during the clinical years and then just failing out everyone beyond that number. It doesn't really matter how everyone performs, they have to fail out X number or get them stuck on internal hurdles and the like because they simply couldn't accommodate more people if they wanted to. So the difference between the guy who makes the cut and the guy who doesn't are pretty insignificant. So yeah, we are saying that there's something F$&@k3d about these schools. And attrition is huge in the equation because at US allo schools its pretty nominal -- a couple of percent in a really bad year, while at an offshore school it's going to be more than half your study group. And that's after having made a six digit investment toward a useless degree. As US schools have increased their enrollment over the past five years, they have, in fact, been taking more people who in previous years would have taken these other paths. But attrition in the US hasn't increased, because frankly that's not an integral part of the business model here. So no, the "graduation thing isn't under your control", that's bogus. You have a lot of people at offshore schools trying to make the most of their second chances, but the schools already know at the onset that regardless of how all if them perform, even if they are all diamonds in the rough, only so many are getting clinical spots.
Second, you seem focused on statistics you can't get. All you get to know that's verified is what gets published by NRMP/ACGME each year. There is no resource which says X % of people with these grades and these step scores don't match. (FWIW "grades" are an undergrad thing anyhow -- in most cases they won't matter if you passed everything (some med schools are P/F) and most of the weight turns on your evaluations, which are essentially abbreviated LORs). And frankly the bigger problem is that the system is not that binary. When I matched I can guaranty that I was selected over many many many people with better numbers. Numbers mattered insofar as they telegraphed how one might do on inservice tests and boards but have little correlation with how you'll be as a resident. Those from offshore schools with much better numbers were screened out from the onset. A lot of my residency's selection process each year turned on the interview and LORs. More nebulous things like eg "leadership" matter -- a common theme in the post-interview discussions was "could you picture this person as chief resident?", never "but this guy has better Step scores". And so that's why you wont get the statistics you seek, nor are they as useful as you'd think. Lots and lots of offshore people had better numbers then me but most programs saw them as offshore grads first, numbers more like third or fourth. They have to be amazing applicants -- in many ways much better than their US counterparts -- just to get to the bottom of the same pile. And that's the real reason more than 50% of those who survive attrition don't match -- the system is stacked against them, regardless of how they do.
It's VERY MUCH like a casino game --about a quarter of those who play have a chance at winning. Sure some of the first 50% separated from their money were bad players, but that's generally the case in every casino, isn't it?