The Republic of Ireland international has featured regularly alongside N'Zonzi and Charlie Adam in the Potters' midfield this season and believes that the summer arrivals have also resulted in an upturn in his own performances this term.
"Everyone has seen what Steven is capable of – he has been incredible for us, and he has really hit the ground running here," Whelan told the club's official website.
"I think that for myself, being able to play alongside somebody who is performing so well gives you a lot of confidence, and that has played a part in my performances this season.
"We bounce off each other in the middle and I think we have worked well, as has Charlie who has played just in front of us.
"With regards to me playing as good as I ever have, maybe I possibly am, but I don’t dwell on my performances too much whilst I am playing.
"I would rather look back when I finish playing and look at when I was playing well, and when I wasn’t. I am just trying to improve all of the time, and hopefully I can continue to do that over the coming months and years."