Didn't Dreger report it?
"As the NHL trade deadline comes and goes, there’s a bit of controversy brewing between Chicago Blackhawks GM Kyle Davidson and Kyle Dubas, his counterpart in Toronto, over reports of a proposed trade that ended up not occurring between the teams.
The deal involved forward Brandon Hagel and goaltender Marc-Andre Fleury, both of whom were traded to other teams prior to the deadline on Monday.
TSN’s Darren Dreger reported on Saturday that the two teams had discussed a deal that would have sent the two players to Toronto in exchange for goaltender Petr Mrazek, forward prospect Matthew Knies and at least one first-round draft pick"
So who nixed the deal and why? Anyways, we've heard he balked at deals, this makes sense to me as entirely plausible.