Eden Hazard headed the home side in front with seven minutes gone, before Tom Huddlestone was sent off for a challenge on Filipe Luis and Diego Costa doubled the advantage in the second half.
Bruce, however, feels Chelsea got off lightly on a number of occasions, particularly when the already-booked Gary Cahill escaped a second yellow card for an apparent dive in the Hull penalty area in the second half.
"We could have defended the first goal better, but the big issue in the game is the Gary Cahill situation," he told BBC Sport.
"The referee shows his intent because he's booked two players for diving and for me Cahill is lucky to be on the pitch for his first challenge.
"If he hasn't dived there, then I don't know what one is. We all know what he's trying to do, he's trying to get a penalty.
"The referee is 10 yards away and there's no excuse. We need him to do his job otherwise it will keep rearing its ugly head.
"Unfortunately, from the first minute, Chris Foy had one of them awful afternoons.
"Today sums up our season. We could have been five or six points better off. I'm still convinced we've got a squad good enough."
Bruce and opposite number Jose Mourinho appeared to be deep in conversation during the second half and Bruce revealed the pair had been discussing the performance of Foy - a referee both have had run-ins with in the past.
"I hope there were no lip-readers out there, or we will both be in trouble," he added.
