His form led to a call up to the senior Wales squad, an opportunity for Patchell to sample his first taste of international rugby.
It was a chance the young playmaker enjoyed, despite Japan levelling the series at 1-1 after their final Test win in Tokyo.
"I went to Japan and I'm over the moon about that. There's no looking back now, you've just got to improve," said Patchell, speaking at the launch of the new Cardiff Blues kit for the forthcoming season.
"Every little kid wants to be able to play for Wales and to tick that off at 20 years old, I was absolutely thrilled.
"Now I'm really looking forward to getting my teeth into this season. We've got a more experienced team with the Blues and we're looking forward to playing some good rugby on the new pitch."
While Patchell played most of last season in the Blues' number 10 shirt, he insists he still sees it as far from his own.
Instead, he is concentrating solely on the region's pre-season preparations at their Vale of Glamorgan training base.
"It's a new season with the Blues and we've got a new pitch and a new kit. The atmosphere at the Vale is wonderful and everyone is working hard," Patchell added.
"Everyone is really excited that we can show our potential this year.
"I've got 20 games more experience and there'll be pressure but that's part and parcel of the job."
Patchell forms part of what looks like a hugely exciting back line at Cardiff Arms Park this year.
Young centres Cory Allen and Owen Williams offer plenty of creativity in midfield and with British & Irish Lions duo Leigh Halfpenny and Alex Cuthbert providing firepower in the back three alongside Harry Robinson, the Blues will certainly test defences with ball in hand.
"There's always pressure and the need to impress the Director of Rugby," said Patchell.
"It doesn't matter if you've played two games or 200 games for the Blues, you've got to push the team and try and turn the screw.
"Nobody expects more from the team or myself than me. There are 10,000 people every week hoping you'll be brilliant. But that is an external pressure rather than an internal one."
After exploding on the scene last year, Patchell is now looking forward to pushing ahead with the Blues as well as enhancing his international prospects.
It's unlikely that he will feature much at outside centre though, a position he played in the second Test against Japan after coming on as a replacement for the injured Williams.
"The last time I played outside centre was the Cardiff Schools Under 11's trials," commented Patchell.
"I was put there to do a job but that's what learning is about. I was devastated after the game, as was everybody else, but it only makes you hungrier to improve when you get another chance.
"The experience and being part of the environment itself was amazing. Everything that went with it was unbelievable.
"Shaun Edwards has a great saying that if you train like a club player you'll only ever be a club player but if you train like an international, you may be lucky enough to be one. That's certainly something I've taken out of it."
At 20 years old and going into his second season as a professional, Patchell's career hasn't got off to a bad start.
And he readily admits: "I still can't get over the fact I'm fortunate enough to call playing rugby my job.
"That's something really special."