McLean has not even played two full seasons, but has already crammed a lot in to a short space of time.
The centre scored a record four tries in his first Test appearance for New Zealand in 2024 and has quickly developed into Stephen Crichton's long-term replacement at Penrith.
He then made his State of Origin debut off the bench in this year's series opener to become the youngest NSW debutant since Payne Haas (2019).
"What we love about Casey (is) he takes everything in his stride - still rocks in with a sleepy head everyday, but once he gets on the field he turns into a different beast," said Panthers captain and Blues teammate Nathan Cleary.
McLean only turned 20 in April and is set to line up at centre in game two of the series in Melbourne next Wednesday, standing in for the injured Crichton.
The Penrith talent will become the third-youngest centre in NSW history, behind only Will Hopoate and current Blues coach Laurie Daley.
"It's probably a case of right time, right place," McLean told AAP.
"I have to give a lot of credit back to my club, the Panthers have helped develop me not just as a player but as a man and (taught me) how to uphold myself.
"Being able to live that way has helped me get through to where I am now."
McLean's rise has been so rapid that he still admits to being slightly taken aback when fans recognise him on the street.
"I get a few more glances coming my way, but I suppose that comes with the job and I'm lucky enough to have a job that is so amazing," McLean said.
"It's surreal, because I feel people shouldn't know who I am yet and then it's cool when I have kids coming up to me.
"I think about little Casey, knowing he would've been starstruck seeing the likes of some of these boys here (in NSW camp) so being to play alongside them is really cool."
As he prepares for his NSW starting debut, it is also worth considering how close McLean would have been to such high honours if he had chosen to pursue a career in the 15-man game instead of league.
McLean, like Blues teammates Cameron Murray and Tolu Koula, played 1st XV at Newington College alongside Wests Tigers prodigy Heamasi Makasini and highly-rated Sydney Roosters halfback Toby Rodwell.
"Playing my last couple of years at school I was in the Waratahs' Gen Blues system," McLean said.
"I was going well in that system and it kind of had me on the ropes, but the final decision came down to my old man (Willie, who played for the North Sydney Bears).
"He was a big part of wanting to follow in his footsteps, he played league and I wanted to try to carry on his legacy."
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