De Koning is out of contract at season's end with Sydney and St Kilda among clubs linked to a swoop for the 23-year-old.
Voss was adamant De Koning's recent omission wouldn't have any bearing on his decision on his future, and that the ruckman knew what was expected of him to return to Carlton's top brass.
"There's a lot of assumptions and conclusions have been drawn about Tom," Voss said.
"Tom is really professional in what he wants to be able to do. There are things he needs to develop in his game.
"We have those conversations all the time around what he needs to be able to develop. He's absolutely aware of that.
"These conversations are happening over the course of since pre-season started. But I also don't think we should stick our head in the sand either."
Voss said the Blues would provide the support De Koning needed as he competed with Marc Pittonet to be first-choice ruckman.
"The right environment is to challenge where we need to challenge and there's a fight for spots," he said.
"I haven't seen him not be up for that fight. He's up for that."
De Koning was "managed" against St Kilda, and then played VFL instead of facing West Coast on the weekend.
The ruck will miss a third consecutive AFL game after he was concussed in the VFL.
"He'd ideally like to be playing and stating his case but obviously has to wait a week for that to happen," Voss said.
"It's not ideal. We don't want to lose any player under those circumstances, but you manage what's in front of you."
