The three-time world champion has faced doubts about his condition throughout the spring Classics, having fallen ill while training in the Sierra Nevada ahead of Tirreno-Adriatico last month. With his performances over the past couple of weeks not lending clear-cut answers, Sagan insisted that condition wasn't so important going into Flanders.
Yet, after finishing 11th, in the select group of 16 behind solo winner Alberto Bettiol (EF Education First), he conceded his illness had held him back physically.
"It's strange that all the television cameras are here, and not with the winner," Sagan joked after stepping off the team bus to a crowd of media and fans.
"I don't think so," he replied when asked if he was the same Peter Sagan as in recent years.
"Yesterday I said in the press conference that you never know how the race will go. Today was just an example of that. It was very hard, and for sure I am not like I was three years ago.
"I'm not 100 per cent like before, like three years ago, but every year is different and I have to just take it."
Sagan rode a quiet race, which ignited on the Muur van Geraardsbergen with 100 kilometres to go but which fluctuated thereafter without really settling into a set pattern.
There were 20 riders left in contention when Bettiol attacked on the Oude Kwaremont with 18 kilometres to go, and Sagan was visibly panting on the final climb of the Paterberg. He managed an acceleration on the run-in, but was unable to launch a sprint to contest the podium positions.
"The race style was a lot different from past years," he explained. "The race was open with 150km to go, and it was very hard race. I think Bettiol took all his chances and he surprised everyone with how strong he was. Also [Mathieu] Van der Poel and Greg [Van Avermaet] were very strong today, but in the end nobody made a big difference – only Bettiol.
"It was pretty hard. Every year is different. I’m not disappointed – it's just a race. Sometimes it goes well, sometimes it goes badly. In the end, I was there. I made a little mistake at the end with the sprint, but that’s how it is."
Sagan has, from the steps of the same bus in the same parking position in the main square in Oudenaarde, bemoaned a lack of collaboration in the past couple of years, with QuickStep's Philippe Gilbert and Niki Terpstra winning solo in 2017 and 2018 respectively.
This time, there were no remonstrations, as he explained that the size of the group simply did not lend itself to a constructive chase.
"Everyone was in the front, the team leaders, and everyone just, you know, wanted to attack and go away, but it was hard because it was a headwind. Then everyone stays put on the wheel. There were a lot of riders and when someone attacked there were still a lot of riders to close the gap," Sagan said.
"To really make the difference, you need to go in a break with three or four riders, as then you can collaborate to catch the first one, but with a big group like this, it’s almost impossible."
Sagan did not seem too downcast, and spent plenty of time answering questions and signing autographs. He still has time to salvage something from his spring campaign, with Paris-Roubaix, Amstel Gold Race, and Liège-Bastogne-Liège coming up across the next three Sundays.
"Well, nothing bad happened, and I'm looking forward," Sagan said, drawing the positives from the day.
"The next Classics are coming and I'm very confident I can get better, because I lost a lot when I got sick. I think it's coming, but we will see.
"I just want relax after the race, and then we're going to think about Roubaix in two or three days."