It's been a difficult week for former Toronto Maple Leafs general manager Kyle Dubas — just days after he was let go from the organization, he is now being reviewed by the National Hockey League Players Association.

“The [NHLPA] is reviewing the relationship between former Toronto Maple Leafs GM Kyle Dubas and his agent at the high-profile Wasserman agency for potential violation of the Certified Agent regulations that govern agent activity,” wrote Daily Faceoff's Frank Seravalli on Thursday.

“NHLPA Certified Agent regulations prohibit agents from representing and providing services to any officer or employee of an NHL club.”

The review was confirmed by an NHLPA spokesperson on Thursday.

Dubas was represented in his negotiations with Maple Leafs Sports and Entertainment by Chris Armstrong, an agent of Wasserman Sports. He also represents Leafs superstar Auston Matthews. Armstrong isn't currently an NHL certified agent and therefore not subject to NHLPA discipline, per Seravalli.

The question becomes: “Are agents working for the same agency, but in a different division or arm of the firm, also prohibited from representing hockey executives on the other side of the table?” wrote Seravalli.

The answer is not at all simple, according to multiple NHL certified agents.

“This is clearly prohibited under the regulations,” one agent told Daily Faceoff on Thursday. “It is an unwritten, understood and longstanding practice that your guy down the hall doesn't work for the other side.”

Chris Armstrong has worked with Wasserman since 2010; the agency's hockey executive vice president Jeff Jackson told Seravalli that he was unaware of a pending review.

“I don't have any direct knowledge of [a review from the NHLPA], but I'm sure that any or all of the certified agents in our hockey department would be happy to answer any questions the PA may have on this matter,” Jackson said.

Cleary, the review in question is still in its preliminary stages. The Wasserman agency represents nearly 10 percent of all players in the NHL.

Kyle Dubas, a former player agent himself, hasn't made any comments regarding the review as of Thursday night.