Do these guys still get paid when they leave but the WWE hold them to sit out the rest of their contracts?
Usually the deal is they'll get 90 days of their downside but can't compete anywhere that has TV (in the US), but you can forgo that pay and show up wherever you want the next day if you really want to. I think Raven in 2003 is the only guy to do that, though.
In the past, ROH was okay to show up at right after a release even when they had a national cable deal, but I don't know if that's the case now.