Andre Santos admits the loss is a big blow.
He told ESPN: "We lost a lot. Van Persie is a high quality player, a big idol of the fans and he had a great championship season in 2011-12, but I am sure the team is much more mature.
"Today we have experienced players and also the arrival of some new players, like Santi Cazorla and Podolski, who are excellent.
"We are well focused, the team is well prepared and well motivated. We have brought in some top quality players and I am sure that Arsenal will have a great campaign in the English league."