The Cherries won 3-1 through goalscorers Antoine Semenyo (2) and Justin Kluivert, with Ryan Sessegnon scoring for the visitors.
Silva told Sky Sports: "Very tough. The way we lost was very tough for us. We had problems in the first 10-15 minutes, they started better than us, we had some difficulties to adjust. And then we lost Lukic, a key player for us, the way we organise on and off the ball, he has been the soul of the team as well. After losing Tete and two strikers, to lose Sasa too was a tough moment.
"Even losing him I thought we started to control the game much better. We knew the offensive movement from them, Semenyo and Evanilson, the way they go direct behind the back line, we knew we had to b aware of it.
"We had some good moments to punish them on offensive transition and counter attack, but we missed the last pass. They had some chances too but no clear cut ones for either team.
"Second half we started better and controlled the game very well, had long possession and the goal is a good example of it. Without a striker we wanted to give more freedom to the wide players like Castagne and Sessegnon, and a great pass from Chuwueze and finish from Sessegnon.
"At that moment the game was completely under control and two individual moments decided the game really. 100% sure they are preventable, the first one when you have two against one on the side you have to be stronger and the second, the shot from 25 yards, we have to make Kluivert go out wide and not make the shot. We are penalised by two individual players that have the quality, power and pace to do it."