McEvoy was holidaying in Cambodia last week when he was awoken by the news that St Kilda was considering trading him to the Hawks.
Speaking for the first time since the trade was completed just a short while later, the 24-year-old admitted his first reaction was shock.
"It has been a bit of a crazy couple of days," McEvoy told hawthornfc.com.au.
"It was last Wednesday morning when I first found out that anything might have been happening, and because of the time difference it was about three o'clock in the morning over there.
"I was coming off only one or two hours' sleep and got my football career tipped on its head, so it was a bit crazy.
"But having made the decision, and had some time for it to sink in, I'm really excited."
McEvoy admitted to sadness at leaving the Saints, where he played 91 games over six seasons, and was a member of the leadership group.
"It was really hard, and I'm still terribly sad to be leaving," McEvoy said.
"I hadn't thought about it at all and hoped I'd be at the Saints for a while longer.
"But it was somewhat taken out of my hands, so I just had to weigh up the option, and the fact that the Hawthorn footy club wanted me to play for them, I was very flattered and really excited to be here now.
"It's a great opportunity for me."
Drafted by the Saints at No.9 in the 2007 NAB AFL Draft, McEvoy fills the ruck hole left by the retirement of Max Bailey.
In return, the Saints acquired young midfielder Shane Savage, along with a first-round draft pick – edging the rebuilding club closer to its goal of having three picks in the top 20 at this year's draft.
McEvoy said he was now eager to prove himself to his new premiership teammates.
"It's a big hole to fill," he said.
"I certainly had an enormous amount of respect for him (Bailey).
"I'm privileged to be asked by the Hawthorn footy club to come here and try and play that role and hold down the ruck position.
"It seems a long way away at the moment, actually playing games.
"I just want to settle in, get to know everyone and try and earn respect around the place."