"I'm disappointed with that tonight. We are better than that. The fans deserve better than that and I want to give them better," the Watford boss told the club's official website.
"They weren't an easy team though; having just been promoted their confidence was high and they brought the game to us.
"When you pick the games that you want to play in pre-season, you pick teams who you think are going to give you a test, but you think you're picking teams that you will beat.
"But as always, I'd rather have these results now than during the season.