"I have learned a lot about my players, myself and the club this year," the Hornets boss has said.
"We have got to change in the way we do things, but we will be back. I'm desperately disappointed, especially for our supporters.
"But Phil Brown and his Hull team have been better than us over the two legs, so full credit to them."
He added: "I thought we were absolutely fantastic in the first half but we then conceded really poor goal from our mistake. After that it was an uphill task but we gave it a real go.
"When you are pushing and trying to get back into the game there is always a chance Hull will counter attack with the pace and power they have and that's what happened."