AIS/AFL high performance coach Jason McCartney has joined the growing chorus of commentators calling for people to get off Jack Watts' back.

Watts was taken by Melbourne with the No.1 pick in last year's NAB AFL Draft, and is still at school, training with the Dees just once a week.

He debuted against Collingwood in the Queen's Birthday match and followed that a week later with Essendon then Brisbane – all losses.

Calls have been made to send him back to play for Melbourne's VFL affiliate, the Casey Scorpions, to let him fill out and get used to playing senior footy against men.

But McCartney, who was the youth and high performance coordinator for the AIS-AFL before recently moving into the job as AIS-AFL high performance coach, said people should stop comparing him with players that have played senior footy for years.

"Jack Watts has copped a bit of heat unnecessarily," McCartney said on Wednesday at Docklands, the venue for the final day of the NAB AFL Under-18 Championships.

"You can't compare him to Nic Naitanui, or Daniel Rich. Daniel Rich has played in two premierships for Subiaco – and has a big, strong body. Nic Naitanui played a year of senior football last year.

"Jack Watts is a schoolboy, who has played four TAC Cup games. He has played in the [U18] championships and came from basketball.

"It's hard to really compare those boys who get the opportunity to play some senior footy, it probably does help them."

McCartney said Watts simply needed time to build body size, which he would be able to do once he had finished his schooling.

"He's a part-time footballer at the moment – he's not even training at Melbourne full-time and he's still playing some school footy."

McCartney said Watts’ athleticism and strong hands would prove an advantage to Melbourne in the long term and rejected the notion he was too slow for AFL.

"He got run down by Alwyn Davey the other Friday night – he's not going to be the first or the last that gets run down by Alwyn Davey,” McCartney said.

"It does look like he's going in slow-motion sometimes, but I think it's just awareness and vision, and that's come from a basketball background."