Eden Hazard opened the scoring for Chelsea 11 minutes into the second half in Saturday's meeting at the KC Stadium, before Fernando Torres made sure of the points late on.
But despite expressing disappointment at his side's performance after the interval, Bruce stressed that Hull cannot be judged on their fixtures against the division's title-challengers.
"The season's never going to be defined by games against Chelsea," Bruce told reporters. "But over the last few months - especially against the big boys - we've kept the ball better and played better as a team.
"(In the) first half we were OK, but (in the) second half we were nowhere near posing Chelsea a threat.
"Hazard, who was for me the best player on the pitch, scores a wonder-goal for them and after that it became a very difficult afternoon.
"We're disappointed in that, but it's not going to define our season.
"We've made a hell of a start to life in the Premier League, so let's hope that continues."
Bruce confirmed earlier in the day that Hull were in talks with striker Nikica Jelavic after agreeing a fee with Everton, while the club has also made contact with West Bromwich Albion over the availability of Shane Long.