Playing the majority of the game in the ruck, Mumford finished the day with 60 hit-outs, the third most ever recorded behind North Melbourne's Gary Dempsey (63 in 1982) and Adelaide's Sam Jacobs (61 in 2012).
It was an effort made all the more meritorious considering the dreadful conditions, and he added 10 touches, nine tackles and a goal to his impressive day's work.
Mumford was named in the initial All Australian squad in his first year with the Sydney Swans in 2010 without making the final team.
But he would have to be right among the frontrunners this year, having helped the Giants to two victories from three outings already.
"He's been enormous for us," GWS coach Leon Cameron said.
"It's not just his ruck work, which you would've seen in the last couple of hours, it's his ability to compete and follow up.
"What that does is Callan Ward, Jacob Townsend, Stephen Coniglio, all our young mids stand that little bit taller and they want to emulate him.
"To have 115 tackles (to Melbourne's 69) is probably mainly due to 'Mummy' leading the charge.
"His leadership away from the ground has been fantastic.
"He's really embraced it and we're rapt to have him at our footy club."
Mumford helped the Swans win a premiership in 2012, but was cut down by injuries over his final years across town.
Now fully fit, the 27-year-old is able to run out games better than he has in some years.
"My body is probably the best it's been in at least the last two or three years," Mumford admitted.
"I'm not having any dramas with my knees anymore, which means I can train more and have more impact around the club as well as on game day.
"It's exciting. Looking ahead to the future, you can just see with the blokes that have gone into their third year, how far they've progressed this year.
"If we can keep doing that week by week, who knows where we could end up in a few years' time?"
Next up for GWS is a clash with the Western Bulldogs in Canberra, when Mumford will battle the incumbent All Australian ruckman, Will Minson.
"I'll be spending a lot of time in the ice baths and down at the beach trying to get myself right for Canberra," Mumford said.
Twitter: @AFL_JD
