He lined up in a 5-3-2 shape, but switched to a more familiar diamond formation at half-time once his side were 1-0 down.
His side looked much better after the break, but still lost due to goals from Andre Gray and Richarlison.
What did Clement say?
Speaking at his post-match press conference, Clement said: "We played really poorly in the first half and I have to take responsibility for that because I chose the shape of the team,
"I chose the line-up and it proved to be incorrect” the former Bayern Munich assistant said. “And I think I did the right thing to make the changes at half-time in terms of the shape and personnel.”
He went on to say: "We took the initiative, had a lot more control of the game and got back in it. There looked like there was only one team who would go on and win it at that point.”
Three successive home losses
The defeat to Watford comes on the back of home losses to Newcastle United and Manchester United, while Swansea have picked up five points on the road to Southampton, Crystal Palace and Tottenham Hotspur.
"I was very close to making the changes before half-time,” Clement said, as his side were very poor during the first 45 minutes. “But I wanted to use the interval to explain exactly what I wanted on the tactics board so I could get the message over more effectively.
"I told the players that when the supporters get on your back it is because they want you to do better and they are demanding of you, that's fair enough."
He then commented: "Then you have to show the character to play in difficult circumstances, to step up and keep asking for the ball rather than going into a shell and not be available to make a better passing option.
"We were not positive enough." Clement claimed.
A recall for Leon Britton?
It’s familiar territory for Swansea fans, as once again club captain Leon Britton looks out of the first-team picture and the side aren’t performing.
It happened when Clement was appointed last season, and he previously said he regretted not putting Britton in the starting lineup sooner, before his side went on a good run to end the season and stay in the Premier League.
Britton has played just 74 minutes this season, and Clement said: “Every player is always available for selection and the players on the pitch have to listen to that though, when the fans are calling for a player who is not even in the squad.
"They need to listen to that.” Clement went on to say. “He is a really good player, we had good players on the bench and I have told the players I am not going to be worried about who is upset they are not in the 11 or the 18."