Fritz and his team-mates stunned Chelsea in Bremen on Sunday with Eljero Elia and Ludovic Obraniak scoring in the first half, before Felix Kroos added a third goal in the 89th minute.
The 2013-14 Bundesliga campaign was a tough one for Werder as they finished 12th, but they produced some strong results in the last few months of the season.
Werder drew with third-placed Schalke and defeated Hoffenheim, Hannover and Hertha Berlin, who all finished above Robin Dutt's side.
Fritz reckons Werder have built on that form in the close-season and started to show against Chelsea that they are a better side than last term's results suggest.
"We did a lot of things well in the second half of last season and now we are continuing that," the right-back said.
"We really worked hard in the preparations but we still have work ahead of us. You can see that we are a step further, but what's important are the matches in the [DFB-Pokal] and Bundesliga."
Dutt, who took over as coach before the start of last season, claimed he saw his team put into practice some of the things they had worked on in training, although he was not getting too excited about the result.
"We need to take our confidence from good actions and not from results," he said.
"The most important thing is that we implement things from training. I saw that over stretches today.
"We need to get more physical to create more consistent chances and not allow as much defensively."
