Jhon Arias, Hwang Hee-chan (penalty) and Mateus Mane struck for Wolves on Saturday.
Nuno said afterwards, "We are disappointed, we are sad, frustrated, and we should apologise. "We should apologise to our fans that travelled, those that are at home and saw a very poor performance.
"It was something that nobody expected, but something that has to make us think and reflect the situation that we are in.
"I need to see the best of them (the players). We all need to see the best out of them. Individually and as a team, we need to see them not making the mistakes that they are making.
"We need to see effort, we need to see reaction, we need to see character, we need to see many things."
On buying in January, Nuno also said: "Other options are coming and the Club is working because we need to rebalance our squad.
"We have problems in many positions that require to be addressed. Those that come in are not going to solve the situation. It's us here that must do much, much better it was very bad today."