The 27-year-old Czech Republic international has struggled to impress since his summer arrival from Paris St Germain and has been fielded in a number of different positions by Sam Allardyce and Kevin Keegan.
"Once I play as right-back, then left-back, then in right midfield or as a defensive midfielder.
"For instance, in the FA Cup fixture against Arsenal the coach wanted me to play in centre midfield like when I played against Bolton, but Jose Enrique injured himself so I was put in defence. I don't like such rotation.
"I like competition, it is useful. There are four equally talented players for my position. I admit that the team composition is up to our coach and don't complain at all.
"But I think we are on the same level, I am not worse than them. Moreover, I showed some good performances at the beginning.
"That is why I am so sad that I don't play as much as I wish to. That is why I don't feel as well as I felt in Brugge or in Paris, but I will fight on."