He will remain with the Hornets until the end of the season, and has left the door open for a permanent exit from the Nou Camp.
"No the Premier League hasn't seen my best," said Deulofeu.
"I played well with Everton and I made a good partnership with Lukaku but didn't play at my best level.
"In Milan I did, but in Everton I was not the same player. In Milan I was more complete so let's see what happens in the next three or four months.
"I want to be a complete player both defensively and by scoring goals. I want to win games, be aggressive in attack and score."
On his future, Deulofeu commented: "I don't know, in the future anything can happen. At the moment I am here until June, so let's see and maybe in three or four months I love the football and I love this team," he said.
"I can't say anything for sure because it would be fake."