I kinda use "Jobber" as a catch-all... Technically a "JOBBER" was a wrestler who was paid to suck.. ala Steve Lombardi from the old WWF days.
I just use it for people who suck..people who have talent(Farnsworth) but always choke.. Guys that are lineup fillers..stuff like that.
Farnsworth is not really a jobber..but since he plays for the Yankees, I have made an exception.