There are reasons why good players are playing Hamburg and Geneva this week, but there is zero reason for Cerúndolo to. He's played plenty of clay matches, and he's done well. He seems to forget that he has a chance to do well this RG. He's overplaying like a mid-50s ranked player.
Djokovic is playing Geneva because he's stunk up the clay season completely and is hoping to salvage his confidence with a win or two on clay before the French. Likewise, Zverev thinks he can gain some mojo on home turf ahead of the Major. For the rest of them, how many of them really think they'll make the 2nd week? Dangerous is only the real mystery.