Since new coach Gerardo Martino took the reins in the summer, Barca have lifted the Spanish Supercopa, taken 34 from a possible 36 points to lead the Primera Division, and are through to the last 16 of the Champions League with two games to spare.
Despite that obvious success though, Barca have found themselves under fire from some quarters for their performances this season under Martino.
Xavi has defended Barca's style of play under the former Paraguay coach, but admits they are still looking to do better.
"I understand that there is criticism because we aren't at the level we were a few years ago, but the style hasn't changed at all - winning the ball back in your opponents' half and then attacking quickly is not playing on the counter-attack," the Spain international told reporters.
"But it's difficult, it depends on circumstances and what a game requires, but we aren't changing our system, absolutely not.
"The team's philosophy is untouchable and non-negotiable. That was Tata's (Martino) message to us on his first day."
He added: "With the exception of the draw against Osasuna, the balance is positive. We've had magnificent results, but there is room to improve, we can improve our collective play.
"We have to be self-critical, we have to think that there are things that can be improved.
"There are times when we feel really good, playing great football, like in the first half against Milan. But we have to play like that for the full 90 minutes."
The defending champions head into the weekend boasting a one-point lead over Atletico Madrid at the top of the standings and they will hope to still be leading the pack come Sunday night following their trip to lowly Real Betis.
Betis have had a tough time of it in La Liga with five defeats in their last seven games leaving them in the bottom two, but they have enjoyed greater success in the Europa League where they lead Group I.
They beat Portuguese side Guimaraes 1-0 away from home on Thursday to earn a morale-boosting result ahead of their clash with Barca, although coach Pepe Mel knows it will not be easy to topple the Catalan giants.
He said following the win: "Today we are very happy, but the next game is difficult. It's hard to beat Barcelona, but we will try to do it."