He brought the colt down from Sydney to give Switzerland a look at the Flemington straight in a jump-out last Friday week.
The tactic worked, as Switzerland was the first to jump before McDonald eased to take a sit on the colt in a race which was run at breakneck speed.
"We've got a great team that got us back on the track," Waller said.
"He just got excited and hurt himself and got agitated and it was just one of those things that young kids do.
"That's all he is. He's a young teenager, he's finding his way.
"He became a man last start, and I thought with a dominant win the writing was on the wall that a Group One wasn't far away, and to win a stallion making race like this, it's a big deal.
"This race, this week, has so many great stories, but for the colts, this is the race you need to win, so I'm privileged to be training these types of horses because I didn't get them when I started, but now it's a privilege."
Waller said with the Group 1 win under belt, Switzerland could return to Melbourne in autumn or perhaps travel, for straight races.
"The beauty of winning a Group 1 race, it takes a little bit of pressure off," Waller said.
"We've got to just now maintain his value, so logically, races like the Newmarket and Royal Ascot would be in our consideration."
McDonald said Switzerland was one of the nicest colts that he has sat on.
He said he was so alert in the barriers, that he jumped in front, but quickly relaxed.
"He's got a lot of talent, he's got well above average ability, and he's got an absolutely brilliant demeanour," McDonald said.
"He's got an incredible turn of foot, and he can sustain it for a long time, and he's got all the attributes to be a top sprinter.
"There are two races here in the autumn that have got a big circle around him.
"He'll thicken up, he'll develop, he'll get stronger and better.
"He's a beauty."