The Roos impressed early when they streaked away to a 29-point lead in the first quarter, but could not sustain that form after losing two players at half-time and finishing the game with no fit players on the interchange bench.
"I think we sort of jumped on them a bit and everything was going well," Swallow said.
"They're a good first quarter side so we knew we had to get off to a good start and that was the thing we talked about during the week.
"Going in at half-time we were pretty confident still, but in the end it was probably just weight of numbers. I think we just ran out of legs at the end."
As the injury toll rose, Swallow admitted the inability of the Roos' midfielders to take a spell on the sidelines started to tell.
"You can lose one player, that probably happens a fair during a game anyway, but it hurts a bit when they're midfielders that are out," he said.
"You're used to coming off for three or four minutes once or twice a quarter, so that's when you really start to notice it, when you're out there for longer and longer.
"We didn't have the fresh legs to be able to run and take them on and get it into the forward line.
Swallow was his side's only multiple goal kicker with two, but felt he could have done better around the stoppages.
"It was nice to get a couple of goals, but my main role is to get hold of it in the midfield and I didn't have such a great day in the end," he said.
"It was a great learning experience to play on guys like Lenny Hayes and Luke Ball … [it’s] something I can call on going forward."
