The goalkeeper told chelseafc.com: "I believe it was the scouting system here and Cristophe [Lollichon], the goalkeeping coach, also had a say in it.
"And I know when Middlesbrough played here at Stamford Bridge last season that he videoed my warm-up.
"So he looked at my technique then and it is great to think that someone would do that. Obviously he was impressed with what he saw and I am very grateful.
"Personally I never would have thought that a club would do that but I was wrong and I am just glad I did a good warm-up!"
The next major step in his Chelsea introduction will be in a week's time when Turnbull and the rest of the squad embark on the pre-season tour.
"I've seen a programme put together to show me the pre-seasons of past in America and it just looks out of this world.
"It is going to be a lot different from what I was used to at Middlesbrough. We went to Portugal last year, to the Algarve which is still pretty nice but this looks like it is going to be a fantastic trip and one I am looking forward to."