The ESPN pundit said the Tottenham Hotspur man was unhappy during Belgium's defeat by Italy.
The centre-back was forced to play on the left-hand side of defence on Monday as the Belgians kicked off their Euro 2016 campaign with a 2-0 defeat by Italy in Lyon, with goals in both halves from Emanuele Giaccherini and Graziano Pelle doing the damage for the Azzurri.
Vertonghen and compatriot Toby Alderweireld were arguably the best centre-back pairing in the Premier League for Tottenham this past season, but Belgium coach Marc Wilmots elected to break up that partnership to accommodate others last night.
It was a poor performance from the Red Devils who, despite a truly exceptional squad of players, look nowhere near fulfilling their collective potential.
"On the pitch, I don't know who it was," McManaman said to ESPN in reference to Belgium's leaders, or lack of. "Witsel wasn't loud. Nainggolan wasn't loud.
"It looked like Vertonghen, but he's stuck in a position he doesn't like to play so he's not happy. I'm interested to know what characters they have in the dressing room."
Vertonghen's Tottenham team-mate Mousa Dembele was also left out of the first XI in another puzzling decision by Wilmots, given how truly brilliant the all-action midfielder was for Spurs this past season.
Belgium clash with the Republic of Ireland - who drew 1-1 with Sweden in their opener on Monday - this Saturday, and Dembele may be back in midfield, and Vertonghen back at centre-half alongside Alderweireld.