If we had power data, we could evaluate this better but from what I have seen, Remco was clearly going all out in that attack and distancing himself quickly from the group. It was just too fast, too furious. He probably knows (and remembers from last season) that if he is in top shape he can keep up his pace after the acceleration. So shape has something to do with it. On the other hand, if he had just followed the group, the data will likely tell him that he would have matched Bernal and co. He was not "dropped as a stone". He could regain his power after suffering for a few km. So in the end it was a combination of bad tactics and lacking top shape but definitely interesting data for the team to work with in preparation of the Giro.