True Fanerer
G.O.A.T.
Gael "Guru" Monfils is one of, if the not the best example of this. Monfils has achieved his worst best results at Wimbledon a total of 6 times in the 3rd round. Ridiculous how consistently he has failed there. Monfils trouble on grass in no secret to any fan that keeps up regularly.
Is there another top 10 player in history with such terrible results at a single slam? Who is close to this? Stretch the ranks out some, if you like and/or vary your levels of "Peak Mugdom".