Walter Mazzarri felt Watford threw away two points as they twice blew the lead to draw 2-2 at Bournemouth.
Goals from Joshua King and substitute Benik Afobe cancelled out headers from Christian Kabasele and Troy Deeney to stretch Watford's winless run in the Premier League to seven matches.
"I think we lost two points. We deserved to win," said the Hornets boss.
"Two mistakes allowed them to score two goals, and in the second half we could have scored another one.
"We saw it again today, we lose some points for mistakes - we pay the highest price."
Mistakes were the order of the day with Bournemouth conceding twice from set-pieces and Watford falling asleep for both home goals.
Jose Holebas' 24th-minute corner was inadvertently flicked on by Cherries defender Steve Cook to Miguel Britos, who nodded the ball back across goal for Kabasele to head home.
Bournemouth grabbed their equaliser three minutes after half-time when Watford lost concentration at a throw-in.
Adam Smith got the ball back from Junior Stanislas and burst past three non-existent challenges before squaring the ball for King, who had a tap-in for his first home goal of the season.
Bournemouth found themselves behind again in the 64th minute, once again from a corner.
Deeney showed all his strength by shrugging off Smith, who virtually had the Watford captain in a half-nelson, to nod Tom Cleverley's corner past a flapping Artur Boruc.
But Afobe had the final say eight minutes from the end as the visitors hesitated again, this time with Kabasele lying injured.
The striker darted into a Kabasele-sized gap in the Hornets defence, gathered Andrew Surman's pass and fired across Heurelho Gomes to salvage a point.
Mazzarri was not impressed with Kabasele's role in the goal.
"He's a very young player but he didn't think about it," added the Italian.
"He had cramps, he could have told me before and we could have done better, but I'm not happy with that situation."
On the plus side for Bournemouth, at least they did not concede three as they had in their previous six matches.
But that minor improvement did not cut much ice with manager Eddie Howe.
"Was it frustrating? You could say that," he said.
"I thought we defended well in open play. We knew set-plays would be a strength for them, they are a really big team, but the manner of the two set-plays is disappointing.
"But I thought it was a good performance. Overall I thought we were unfortunate not to win.
"The character of the team was superb to come back from losing, and the impact of the subs should give us a huge boost."