The Scot had led his side to five consecutive draws at Stamford Bridge prior to Saturday's game, but admitted that his side ultimately only had themselves to blame after a couple of instances of poor defending.
"Maybe that £400m difference might have showed up after 15-20 minutes, eh?" he said. "I think we've been here to Chelsea and they've caused us more problems at times and we've had to defend harder.
"Today, we gave them the first two goals. I thought our defending on the first one and second one was terrible and they didn't really have to work particularly hard.
"The second goal was a killer because we've been 1-0 down several times coming here and we've always been in the game, given ourselves a chance. To lose a goal just before half-time made it a mountain to climb."
Following the loss, Everton remain in 13th place in the league on seven points.