The Blues have became a changed side under Thomas Tuchel, with no other club in Europe recording more clean sheets over the past three months.
"It was important to improve the defensive record we had," Azpilicueta told the club's webeiste about their defensive improvement.
"We were conceding too many goals and we were not solid enough. In football it is difficult to win every game 3-2, 4-3, 4-2. Sometimes you have to win 1-0 and have a strong, solid performance at the back.
"As a team we defend together, and we work together with the same idea. It's what we have improved a lot.
"Also when you have the attacking players we do doing an amazing job every single game, pressing high, every bit helps the defenders. Working together with the same goal is key in achieving the results."