TY VICKERY'S poor aerobic ability is what holds him back from being considered among the better big men in the AFL. 

That's the opinion of former Port Adelaide premiership coach Mark Williams, who spent the past four years working with Vickery at Richmond. 

"His aerobic running ability is the one thing that holds him back," Williams told SEN radio on Monday of Vickery, who joined Hawthorn as an unrestricted free agent at the end of last season.

Williams also left the Tigers at the end of last year and is now coaching AJAX in the Victorian Amateur Football Association.

"When it comes to running around the ground, that's where Ty struggles. He's not elite in that respect." 

This was despite his father John Vickery being a noted fitness guru, Williams added. 

But before Hawthorn fans think they might have been sold a lemon, Williams said the 26-year-old would still bring plenty to his new club this year. 

"His marking ability inside 50 is outstanding and he's an excellent shot for goal and if you compare this with resting ruckman up the ground he's better than them," he said. 

"He is a wonderful team man who does care for the group."

Williams added there was still time for Vickery to improve his aerobic fitness.

The Hawks have earmarked Vickery to play a similar sort of role to that played by David Hale during the 2013-2015 premiership years, which is to contribute a goal or so a game, and take some contested marks or at least bring the ball to ground.

Vickery kicked 158 goals in 119 games for the Tigers, with a best return of 36 majors from 22 games in 2011.

Meanwhile, Williams revealed that two-time tennis Grand Slam champion Lleyton Hewitt wanted to make the switch to football.

"Not many people would know this, but Lleyton, while he was playing and … right up the top, and Roger Rasheed was coaching him, he would spend time training at Port Adelaide," he said.

"Lleyton rang me prior to the rookie draft and because of his love of football and because of his love his dad and his uncles had done … Lleyton said: 'What if you put me on the rookie list?'"

“I was prepared to put him on the rookie list and I had Roger Rasheed ringing me saying, 'No, no, you can’t do this'."

Despite Hewitt's relative lack of size (178cm), Williams said the tennis star's fighting qualities could have helped him succeed in the AFL. In any case, the promotional aspect would have been irresistible for Port.

"Because of his relationship with me and his family, I could see he had nous when it came to footy," Williams said.

"Maybe he would sit in a forward pocket, maybe he wouldn't do anything but train, but imagine the amount of publicity it would have been around the world to have this guy who was certainly in the top one or two at that time, and he was prepared to walk away (from tennis) and wanted to play footy.

"There's a few skinny runts that have done OK. He would bite and scratch and do anything possible to succeed."

- with Dinny Navaratnam

Mark Williams in his role as Richmond assistant coach. Picture: AFL Photos