For whatever reason, sometimes I am only able to find one card of certain players. To be considered a One-Card Wonder, a player must have been active since 1991 (when I started paying attention).
Chad Fox was part of the ill-fated closer by committee approach Boston took into the 2003 season. Fox was viewed as a low-risk, high-reward signing when he was acquired after pitching in just three games in 2002 for the Brewers.
Unfortunately, the reward part never paid off. Fox pitched in 17 games for Boston in 2003, going 1-2 with a 4.50 ERA. He did strike out 19 in 18 innings, but he also walked 17 and gave up 19 hits, for an unforgivable WHIP of 2.00. Fox was released in late July and ended up with the Marlins.
The only card I own is a 2003 Upper Dec 40 Man card.