Dier has been utilised in a defensive midfield role throughout the season so far, but he dropped back into a back three at Vicarage Road.
And Pochettino explained: "We play always with Eric like a holding midfielder but the way that they play and what we analysed, we found that they play a lot of long balls to make it dangerous for the opponent," he said.
"So it was a good solution to give calm to the team and manage the game from the back.”
Tottenham’s win over Watford was a very hard fought one, and they left it late to secure the three points.
Spurs took the lead through Erik Lamela, before Odion Ighalo equalised for the hosts.
The match then turned on a red card which was awarded to Nathan Ake, as Spurs made their numerical advantage count and scored through Heung-Min Son in the last minute.
Tottenham’s win over Watford has moved them up to third place in the Premier League table.