After playing two games as North's substitute earlier in his debut season, McKenzie took a hastily arranged two-week break from his VFL commitments with North Ballarat to accompany Ziebell, who had just been controversially suspended for four matches for a bump on Carlton's Aaron Joseph, to Utah.
North sent McKenzie, its first pick in last year's NAB AFL Draft (No. 18), in the hope of fast-tracking his efforts to improve his aerobic fitness.
In Ziebell, the Roos knew they had the perfect role model for McKenzie. Like McKenzie, Ziebell had been drafted, in 2008, with aerobic fitness one of the few chinks in his football armour.
In his first season at Aegis Park, McKenzie had already seen how hard Ziebell worked on improving his fitness, squeezing in extra aerobic sessions on top of the club's standard training.
So McKenzie expected Ziebell's work ethic would set a lofty benchmark for him in Utah. And it did.
But the skilled left-footer learned more than just the value of hard work after spending two weeks with Ziebell. He'd also learned the all-encompassing professionalism an AFL footballer has to embrace to be successful.
Specifically - and unexpectedly - he learned how to grocery shop and even came away with a few appetising recipes.
"It was awesome to go to Utah with Jack," McKenzie told kangaroos.com.au this week.
"It was good to bond with a leader of the club and to see how hard he trains. Especially training with someone who had the same sort of aerobic capacity as me when he started his career, to see how much he's improved.
"He pushed himself to the maximum, which pushed me to the maximum.
"But everything about Jack is really professional. When we'd go and do our grocery shopping in Utah, Jack would make sure we got the perfect food to eat.
"We had a kitchen back at the hotel where we were staying so we cooked our own meals some of the nights.
"It was just a good learning curve. Now that I'm living with my brother, when I do the grocery shopping I try to remember what Jack and I bought in Utah and the meals we made."
McKenzie has improved his fitness since joining North, but knows from Ziebell's example - and that of 2009 No. 5 draft pick Ben Cunnington - that he'll have to be patient and keep working hard.
"You're not going to go from a poor aerobic capacity to a perfect aerobic capacity in the click of a finger," McKenzie says.
Accordingly, this pre-season McKenzie is going to take it one time-trial at a time. This week, he ran a 2km time-trial and completed other fitness tests. He is determined to better those marks when the Roos do their next round of testing prior to Christmas, then again at their post-Christmas testing and so on.
Complicating McKenzie's fitness drive is his equally pressing need to bulk up.
McKenzie readily acknowledges that the intensive running sessions he's doing at the moment will make it harder for him to put on weight in the gym.
But he said the biggest thing he took from his two AFL games - North's losses to the Western Bulldogs in round seven and Port Adelaide in round eight - was the need to improve his strength and body work.
So he will complement his pre-season running with intensive weights work and regular protein shakes, as well as working with senior North assistant coach Darren Crocker on his body positioning, "wedging" techniques, and "ball protection".
Asked about his goals for next season, McKenzie says he is simply focusing on having a strong pre-season, getting a game in next year's NAB Cup and holding his spot in North's team from there.
McKenzie is not fussy whether that spot is in the midfield or, as is more likely, across half-back. However, he points out that he did not play regularly as a defender until his final year as a South Australian under-18 representative, and played a lot as a forward during his junior days.
But for now Utah is calling McKenzie's name again. On Friday, he will depart with a much larger North contingent to again push his fitness limits in the thin air of Utah.
Despite knowing the physical pain that awaits him there, McKenzie welcomes it, knowing high-altitude training can help him fast-track his fitness to where it needs to be.
Ziebell, for one, is confident McKenzie will get there in the end.
"Everyone who steps into AFL has a couple of things to work on in their first couple of years," Ziebell told kangaroos.com.au.
"Everyone who gets drafted these days has talent, but talent can only get you so far.
"But Brad has the appetite to work hard as well, which will hold him in good stead."
Nick Bowen covers North Melbourne news for AFL.com. Follow him on Twitter: @AFL_Nick
