Nuno Espirito Santo admits Wolves needed time to grieve after last season's FA Cup heartbreak.
They host Manchester United in the third round on Saturday, 10 months on from their semi-final collapse.
Wolves blew a 2-0 lead to lose 3-2 to Watford after extra time at Wembley to miss out on their first FA Cup final since 1960.
They knocked United out in the quarter-finals en route to the last four in 2018-19 but head coach Nuno revealed it took time for the squad to get over their exit.
"We overcame that. It was only a couple of days of grief. It was very sad," he said.
"You need to grieve. When you lose someone the best way is to grieve. Not only me, I think everybody involved felt that sadness. But that it made us really stronger.
"I grieved a long time ago, I'm not grieving now. After the defeat we played at Southampton and didn't perform well.
"Clearly we were in that situation, we were sad, we weren't able to raise ourselves again.
"But then we went away for a couple of days, we made our grief and we came back stronger. One thing that happens in life is you go low and then you stand up and fight again. This is us."
Losing Vallejo stretches an already thin squad and Nuno wants new additions in January.
"We need to bring players in. Who and which positions I will not share with you unfortunately," he said.
"That is not the right thing to do, especially when there are so many names going around that don't make sense.
"We need players. Now I think is the right moment to start working on that. The transfer window gives you the chance to bring things that can improve you. That's what I'm looking at."