Sullivan, a product of Napier Boys' High and Kings College said he was happy to have had the starting opportunities of the past few weeks but realised he still had plenty more to learn.
While he admitted it was a natural mindset to want to be a starter, he said it had been an honour to gain a contract with the side so early in his career.
"At the moment it is looking good but I just have to keep performing, keep training and doing what I'm doing," he said.
The differences from club rugby and the national championship were marked when stepping up to the Super Rugby level.
"It's physical, it's quick, it's challenging on your body, it's challenging mentally so you're always thinking, always on your toes and you have to keep getting better every week," he said.
Nothing changed with the move to trans-Tasman competition. The same impacts were involved, the same thinking and it was important to stay on top of that, in spite of how different it might look to the average punter watching on television.
It had been good to get across to Australia for the opening round, something he had only done previously when playing for New Zealand Schools, and he had his first taste of Melbourne.
While he has been playing at fullback for the Blues, and for Auckland, which is something he is concentrating on developing to the full, he still harbours a desire to return to first five-eighths.
That's challenging some of the norms for the role as he stands 1.90m (6ft 3in).
"I've played there for a while, just at this grade I'm concentrating on fullback and making sure I can put my best foot forward for the team," he said.
It helped that Blues coach Leon MacDonald had plenty of experience playing fullback.
"I'm still learning, it's only my second year at fullback and Rangi [MacDonald] has helped me a lot."
That was down to painting pictures of opposing first five-eighths might do on attack and the defensive strategies involved in coping with that.
"It's things like that, he's given me a better understanding of where I should be, and where I shouldn't be, where I want to finish, where I can pop up," he said.
Sullivan has made an early impression with his booming left foot and was working on developing the same with his right.
He's also handy with long-range penalty goals as he showed in Sydney with an effort from halfway. He has always been a specialist in that area and in the Blues' structure with Otere Black operating up to and around 40m out, Sullivan steps in for the longer shots.