It isn't exactly known, but what is known is that Matt and Pat had the breakup and are no longer friends.
The speculation is that Matt was getting bored with the channel and was low-effort with a number of projects towards the end (the podcast and Shitstorms come to mind) but was still the main majority partner/channel owner which would have him clash with Pat and/or Woolie, who were still into the channel (and the podcast, which is alleged to be hugely popular). Matt started in gamedev QA (pre youtube) and it looks like he's getting back into it and that's where his passion is - he's helping out on "The Takeover" (which doesn't look all that great, TBH) and is working on another horror game who's name escapes me.
We aren't sure where they started drifting apart, but Matt and Pat have always been two very different people. Matt takes youtube/LP seriously as a business and talks about "branded content" and such, where as Pat streams in his pajamas. They've had two very different approaches through the years about LPs in general. Matt typically liked more esoteric games (old Wii games few people have heard of) where as Pat was more of a "here are the games I like" guy. They allegedly didn't agree on some business items (Liam's cut/pay, crossover stuff, travel requirements, a dedicated office).
It's also unclear (still) about the Liam situation and how that feeds into the current drama. It's clear that Liam doesn't like Pat for some reason, but it's important to point out that Woolie is regarded as a "real stand up dude" and is (or at least was, for a long time) Liam's actual best friend - It's very unlikely that Woolie would stay friends/business partners with someone who savaged his best friend, so it likely was just a dumb argument kind of thing. It also doesn't help that Liam frequently acts like an absolute basketcase faggot on twitter/twitch/etc over the smallest shit. It is still worth mentioning, though.
Whatever the case, Matt has moved on. It isn't just Woolie/Pat he doesn't interact with - it's most of the youtube community. The SBFP community (Plague of Gripes, SuperBunnyHop, 2snacks, etc) as well as anyone who isn't his wife or Liam. He does some LPs, but most of his videos are review/commentary instead of full LPs - where as Pat and Woolie have stuck to streaming/podcasting like nothing ever happened.
