In terms of actual talent, the worst major-league pitchers are the ones that play only a handful, or maybe even just one singular game. The fact that they get a shot and that team, or any other team, aren’t willing to give that person more shots is telling.
However, the pitchers who are more memorable for being bad usually have an extended career. Lou McEvoy falls more in this camp. He doesn’t have the Yankee record for highest ERA or anything. However, he pitched a lot, and was bad, and might be the worst Yankee pitcher ever.
McEvoy started out in professional baseball in 1926 with the Chattanooga Lookouts.