This all comes from, according to ProbationOfficer2035, a conversation in the background while playing with Twitch streamer OohTally, Coward's wife.
NFL trade leaked via Warzone
ProbationOfficer said in a Reddit thread that, while playing Warzone "with randoms," he ended up with a female teammate, which after some digging, turned out to be OohTally. "She had her mic on and I could hear her husband talking in the background about a 'deal'. Then something was said about he would love to play in Pittsburgh."
In the Reddit post, Probation stated that Tally was reluctant to give more information, but did confirm her husband was an "NFL player," soon to be revealed as Coward, as OohTally has pictures with the Bears offensive guard on social media such as Twitter and Instagram.
It remains to be seen if the deal will end up happening, but it seems Coward has hinted at it via Twitter with a mysterious comment.