The center back expressed his disappointment at not playing regular games, but insists the club is stronger than during the "madness" of Andre Villas-Boas' reign.
The 26-year-old central defender has had to compete with John Terry and David Luiz, but is set to play against Manchester United on Sunday with Terry serving a four-match ban after the FA found him guilty of racially abusing Anton Ferdinand. And while the former Bolton defender has not played as many games as he would have liked, he believes life under Di Matteo is better than the "madness" of Andre Villas-Boas' time in charge of the club.
"It has been frustrating for me at times this season, I'm not going to lie – like on Tuesday night in the Champions League [against Shakhtar Donetsk], the rotating," Cahill told Sunday Mirror Sport. "I think you can accept it if you are playing the same amount of games as everybody else. That's the only way you can come to terms with it.
"When I first came into the club, it was a bit of a whirlwind with all sorts going on. Trying to find my feet was a bit strange. It's unsettling for a start and then to come into the club that was unsettled at the time, it was double madness.
"But, 100 percent, Chelsea is now a different club from the one I joined. It took a couple of months, but everything has settled down now and I knew that would happen."
In Terry's absence, the Englishman will be playing alongside Brazilian Luiz, with whom he believes he has struck up a good partnership.
"It seems to have gone well," Cahill said. "But it's gone well whatever pairings have been put out. I've done well with JT or David. I enjoy playing with both."
Cahill made his debut in a thrilling 3-3 encounter against Manchester United last season, with Chelsea throwing away a three-goal lead during a chaotic period for the London club.
"My debut against United was a crazy game. At 3-0, I thought it was going to be a dream debut. It was all going to plan and then suddenly, as you come to expect from Manchester United, it all turned around."
Cahill believes he can prevent Wayne Rooney from firing United to victory on Sunday afternoon as he know the forward's strengths from playing with him for England.
"It helps that I know a lot of Wayne's strengths," he said. "But like all players of that caliber, he can do the unexpected."