"I have a massive drive. I want to prove my critics wrong," said Seaman.
"Arsenal had more or less told me they didn't want me. I want to prove them wrong as well.
"I was waiting for an offer from Arsenal and the offer made was not what I wanted.
"It was quite an easy decision to make but it was hard to leave after 13 years at Arsenal.
"I wanted to play for another year and I knew I wasn't going to get that opportunity at Arsenal. I would have been number two."