Naitanui's 2013 campaign was severely hampered by injury, with groin issues restricting the athletic ruckman to just 11 games.
Cox, a six-time All Australian and a veteran of 273 matches, said he would take a back seat to Naitanui this season and spend more time up forward.
"Certainly if Nic is up and running and fully fit he is our No.1 ruckman," Cox told News Limited.
"But I have also certainly said throughout my career that whoever is in there on the ball at the time, has got to be known as the No.1."
He said that new interchange cap would require players to spend more time in different positions "and for myself and Nic or Scotty [Lycett] or Callum [Sinclair] that is spending time forward as well.
"I suppose that's back to 2011-12 where we spent chunks of games forward where we weren't rucking in the forward line."
Cox expected Naitanui to return to full training in time to feature in the Eagles' NAB Challenge matches, having recently increased his training.
"I think he will certainly be back into full training shortly," he said.
"His running loads are great and his body is pulling up really well from all the training programs so far and hopefully it just continues from that as we ramp it up.
"He's such an important part of our footy team to make sure that his work rate is really monitored throughout the year as well and that he can front up pain free."
