Altidore's previous spell in the Premier League saw him score just once in 28 appearances for Hull City, but after a successful stint in Dutch football, the American has revealed that his confidence has improved upon his return to England.
The 23-year-old told the Sunderland Echo: "I think that I just became a better player in Holland than the one when I was at Hull.
"On and off the ball and linking up with the players around me, I just got better. It's that simple. I've become a much more confident player since then."
Altidore netted 38 times during his two seasons with Alkmaar.