However, the 27-year-old has regained his self-belief for the coming campaign.
"I do feel I am ready to give it my best shot this season," de Visscher told the club's official website.
"I remember last year, I could not walk after three days' pre-season. This year, though, pre-season went by easily, all the running stuff, so I think I have become stronger.
"Football-wise, it is still a very different game from the one we play back in Holland."
But he added: "I feel I am more prepared for the matches this campaign. Everything last season was very new.
"I will be honest and say last season there were a few times when I wondered if I had made the right decision about coming to Scotland, going to a foreign country.
"I am happy with my choice though. Aberdeen is a great club to play for."