I have no idea about the field of the WOW TCG tournament but calling Matignon a mediocre magic player is just wrong. The guy won world, came second on a pro tour and was tied for player of the year(he lost the tiebreaker match though). His DCI suspension was due too him leaking a whole set(breaking nda essentially) and not due to anything related to competitive play.
As for M+, it's pretty much the only competitive PvE they can realistically support and I'm happy to see them try. But I doubt it will ever be balanced.