We can deduce some things applying logic. Apple subs would obviously be down this year, minus all the free subs that were given out not just in the U.S., but around the world. Most of those -except STH- don't exist this season. Also, the jump from under a mil subs to a final of near two mil subs, MLS said a majority of those new subs came from "South America and Europe" (for Messi, obviously) which isn't a bad thing business wise but does nothing for "U.S. viewership."
So less people with Apple subs = less people watching on Apple. Certainly less in the U.S. since majority of the "for Messi" subs would still come from outside the U.S..
With less people watching on Apple you'd assume more people would then be watching on FOX/FS1, as that would be their only option to watch MLS. Yet, the last Saturday match on FOX did 196k ... under 200k, on a Big 4 network! That's nearly impossible to do for a live sporting event, yet that's MLS.
The usual response to poor MLS linear #'s this season and last is that "millions are watching on Apple!" Which defies logic, of course.
Another way to find a true viewership number for MLS is to eliminate the games that are also streaming. Which happens when MLS teams play in the Concacaf Champions Cup -- a competition infinitely more important than largely meaningless MLS regular season matches. So linear-only, all MLS fans watching and those matches do numbers like 88k on FS1. Which sums that up.
As for streaming, the standard always is hide the numbers unless they're good. That the only numbers we've ever heard for Apple MLS matches are last season "a couple Messi games did over a million" (again, worldwide, so not a U.S.-only number) says that not much else is being watched, at least to any extent worth mentioning, giving a general idea of or even hinting at.