Terry has been missing since early last month with a knee injury, in which time new boss Rafa Benitez has taken charge - but they have won just once in in seven games, the midweek win over FC Nordsjaelland.
Captain Terry had used his programme notes for Wednesday night's Champions League game to brand results during his injury absence as "simply not good enough", demanding more "fight and desire" from his team-mates.
And Cahill acknowledged the public dressing downs were warranted.
"If there's a time where it needs to be done then, sure, it's a positive, as long as it's taken in the right way," the England defender said.
"You have to dig in as a group. That's the only way you can go forward."
Cahill declined to reveal whether Terry had repeated the sentiments expressed in his programme notes to the players but added: "We've had meetings before at the club, definitely.
"When we need them, we've had them and they stay within the club. It's right that the players are upset. They don't expect to lose games.
"They expect to win the majority of games you go out and play. It's not been happening so it's going to be upsetting players and everyone involved.
"I don't know what's gone wrong - that's the honest answer. It's the same group of players. The players have been asking that question themselves and we don't know really.
"Where do you point the finger? It's obviously stuff you need to work on in the training ground. It's the same group of players who started the season beating teams and scoring goals and keeping clean sheets.
"There's no reason why we can't get back to that but we were hoping it would come sooner. We've been waiting for that win."
Chelsea are already 10 points adrift of leaders Manchester United and Cahill added: "We can't afford to slip up many more points in the Premier League. We need to get back to the form we had at the start of the season."