Speaking to the Ipswich Evening Star, the 33 year old Dutch defender said: "Against Osasuna we gave too many chances away and we need to work on that. In the second half we could not keep the ball and all we could do was defend.
"It's not just the back four, you defend as a whole team. If the midfield or strikers do not hold the ball up then it comes back straight away and that makes it hard for the defence."
Wilnis ironically played at left back against Spanish Primera Liga club Osasuna, filling in for Matt Richard who missed the game with a slight injury. Former Burnley centre back Drissa Diallo filled in at right back.