The Nigeria attacker is a target for Chelsea and QPR.
"Roberto Martinez has brought this player on and he needs at least another year with Roberto to become a top player," Whelan told ESPN.
"We have offered him a new contract but it seems the agent, more than the player, wants to move him on - at least that is the impression we are getting.
"He needs games and he won't be first choice at Chelsea, I wouldn't have thought.
"We don't need to sell him with 12 months to go on his contract because he is under 24 so wouldn't be going on a free transfer.
"Ideally we would like him to sign a new contract, or a club like Chelsea would have to be realistic."