I have been reviewing some results... And apparently Mario Deslauriers could be just about the unluckiest Olympian ever.
He contested 4 show jumping events in total during 1984 and 1988. In 3/4 of those events he placed 4th! Every time very close to the podium.
1984 team - 0.75 penalties away from the bronze
1984 individual - contested the jump-off for bronze
1988 team - 1.25 penalties away from the bronze