The German champions scored three times in the dying stages of the Champions League match to add embarrassment to the scoreline at the Tottenham Hotspur Stadium, with former Arsenal winger Serge Gnabry netting four in total.
Jenas believes the nature of Spurs' collapse is a pointer to the fragility of the team's morale at the moment and suggested the players were not following instructions from coach Mauricio Pochettino.
"This is a big wake-up call for this football club it really is," Jenas told BT Sport.
"They had a moment to figure out what they wanted to be, how far they wanted to go.
"You can lose games of football, but this is a battering from a top European club who have been there and done it on many occasions.
"It has been a tough couple of months for this group of players, this football club."
He added: "These are the types of results where do you start to look in the dressing room, you start to ask those questions - are they reacting to what is being asked of them?
"This scoreline tells me 'no' at the minute, this scoreline is a shocker.
"It’s the capitulation, it’s that moment of 'it is not going great, let’s feel sorry for ourselves'.
"At what point do you say 'no, the opposition are not scoring any more goals, it is not happening'?"
The match started well for Tottenham with Heung-min Son giving the home side a 12th-minute lead, but they were behind by half-time as Joshua Kimmich quickly equalised and Robert Lewandowski struck right on 45 minutes.
Gnabry then hit two shortly after the break to earn Bayern a 4-1 advantage, and despite Harry Kane pulling a goal back, Tottenham fell apart towards the end of the game.
Spurs now drop to third in their Champions League group behind Bayern and Red Star but will have the opportunity to climb back into second later this month when they host the Serbian champions.
In the Premier League, a tricky trip to Brighton awaits Pochettino's side on Saturday as they attempt to climb into the top four.