Anthony McConville said a clash between Mumford and Crows player Jared Petrenko warranted full AFL explanation.
The League's Match Review Panel did not refer to the clash when it released its round 11 findings.
In the clash, which also resulted in Petrenko sustaining a serious shoulder injury, the Adelaide player's head made contact with Mumford's face, requiring the Swan to have surgery this week and be sidelined for up to a month.
"At the end of the day, it is disappointing, really disappointing," McConville said.
"A player is supposed to be protected from this, yet here we have my client missing four weeks and sucking food through a straw.
"It wasn't even written up in the reports (of the Match Review Panel). That is the most disappointing part of all this – that it was just dismissed. Shane is as disappointed as I am."
While McConville stressed he had no personal issue with Petrenko himself, he strongly argued the AFL needed to better explain its system.
The AFL said the Petrenko-Mumford incident was similar to the Lindsay Thomas-Ben Reid clash from round one, where 2013 tribunal guidelines allowed the Kangaroos player to escape sanction due to an "out clause" existing for players who inflict damage on an opponent through accidental use of their own head.
That guideline is expected to be removed before the start of the 2014 season.
"We understand the rules and know that footy is a contact sport. Shane has been on the receiving end of those rules, and that's fair enough," McConville said.
"But if the tables had been turned on the weekend, and it was Shane doing this to a smaller player, then there would have been an outcry."
