Rogic started Monday's 1-1 draw with St. Johnstone but was replaced in the 68th minute with scores still locked at 0-0.
The 27-year-old has been selected in each of the Hoops' last 13 games after being linked with a move away from the club at the start of the season.
However, in an interview with Football Insider, Whelan said Rogic should no longer form part of manager Neil Lennon's plans.
“Rogic has struggled this season, he really has,” said Whelan, now a pundit for BBC Radio Leeds.
"He used to be the player you could rely on to produce a moment of magic, to do something special.
“But we haven’t seen much of that recently, even though the whole team has been terrible.
“You look at him and he’s a shadow of his former self, like quite a few of them. He’s not fit to wear that famous jersey, and he’s not the only one.”
Celtic sit second in the Scottish Premiership, 13 points behind rivals Rangers and with two games in hand.
