Almunia said: "Theo was too nice on the pitch in the last two years. This season you can see when he gets tackled he gets furious sometimes. That's a good thing and shows he is growing up.
"I spoke with him and told him that you have to be a bit more aggressive and not be so nice on the pitch.
"For me, Theo is the most exciting young English player I've seen by far. His skills are incredible."