The Argentinian was sacked as Spurs manager last month after overseeing a run of just six wins in 24 matches in the Premier League.
He guided Spurs to the UEFA Champions League final last term, but a downturn in domestic form had seen the north London side almost miss out on the top four last season, and Pochettino was sacked with Spurs lying 14th in the 2019-20 Premier League table.
Jose Mourinho has come in and overseen three successive victories which have moved Spurs back to fifth.
But Vertonghen said the players have to take some blame for the results that led to Pochettino's exit, per Goal's Chris Burton:
"Our displays [under Pochettino] were not up to our standards. We’re all responsible. He put us on the pitch to win and we haven’t been doing that like we should, so everyone feels responsible."
Mourinho returns with Spurs to former club Manchester United on Wednesday nearly a year on from being sacked from the Old Trafford job.
Although the situation improved at United in the immediate aftermath of the Portuguese's departure when Ole Gunnar Solskjaer was appointed interim manager, the Norwegian's magic touch has deserted him recently.
The Red Devils have won just four times in the league this season and are down in ninth.
If Mourinho's Spurs side beat United on Wednesday, they could find themselves in the bottom half of the table going into the busy Christmas period.
A win over their former manager, though, could put the Manchester giants as high as fifth ahead of Saturday's trip to Manchester City.