Hazard was voted England's PFA player of the year last season after scoring 19 times for Chelsea, who romped to the Premier League title by eight points ahead of Manchester City.
The 25-year-old Belgian has struggled in this campaign, however, scoring his first goal in Chelsea's FA Cup fourth-round win over MK Dons last month and his second in the Sunday's fifth-round defeat of Manchester City.
"We are a much stronger squad if we have Eden playing at his best and have a better chance to get good results," defender Azpilicueta told Standard Sport.
"Playing like this, Eden is like a new signing for us. It is better to have Eden in his best form now than at the start of the season. It is at the end of a season when you are playing for trophies."
Chelsea must overturn a 2-1 first-leg deficit when they face Paris St Germain at Stamford Bridge on March 9 to reach the Champions League quarterfinals and play Everton in the FA Cup last eight three days later.
They are 12th in the Premier League table, 20 points behind leaders Leicester City with 12 games left.