Smith, currently captaining Australia in the second Test against West Indies, remains unsigned for this year's tournament, with all rosters having been finalised.

He confirmed on Wednesday his management were in discussions with Cricket Australia after he missed out on the back-end of last year's BBL tournament as he had not registered for the COVID-19 player replacement pool.

"Without a doubt this game is crying out for the best players in the world and the best players in the country, and Steve Smith is that player," Sixers veteran Steve O'Keefe told reporters on Thursday.

"If I'm Cricket Australia and I'm sitting around in a room it would be almost number one on my list - get the world's best players."

The BBL has been dogged by falling crowd numbers in recent years and the paltry turnout at the summer's first Test in Perth would have been a worrying sight for the game's administrators.

O'Keefe argued the league needed star players like Smith to keep audiences interested.

"We're seeing Steve probably play his best cricket since 2013," he said.

"I know for a fact if you've got him even for two or three games for the Sixers, you're going to put an extra 5000-10,000 bums on seats, so do what it takes to get him back on."

Sixers allrounder Sean Abbott agreed.

"We'd love to have him on because he's great to have around the group and I'm sure everyone at home wants to see Steve Smith playing Big Bash," he said.

With the Sixers' 18-man squad already filled, Cricket Australia would need to dip in to their marketing spend to help cover the cost of Smith, as they did to lure David Warner to the Sydney Thunder.

"Steve Smith is a local talent who loves the Sixers and would have played for basically nothing last year," O'Keefe said.

"Why can't we find a way to get this guy involved?

"It's just a no-brainer for the game, and if Steve can fit it in let's get him in."

Meanwhile, Melbourne Renegades captain Nic Maddinson told AAP Cricket Australia made a mistake in not allowing Smith to play last season.

"Any time we can have our international players play in the Big Bash, we should be allowing them to," he said.

Adelaide Strikers captain and former Test paceman Peter Siddle also said the addition of Smith would help address the drop in crowds for the tournament.

"The fan following (Smith) has is massive," Siddle said.

"He's the greatest Australian batsman of recent times. He's someone you want back."

Australian Associated Press