The Ecuador international was not involved on Saturday as Chelsea moved in to hijack Liverpool’s £111 million move for the player.
While the deal has not been completed, the midfielder is now expected to head to Stamford Bridge for a British record fee.
Albion did not require his particular qualities in the season-opener as they beat Luton 4-1 at the Amex.
But De Zerbi wants a replacement for Caicedo to be brought in rather than, as on Saturday, giving his midfield a different look.
Roberto De Zerbi said: “Yes, I think we need another midfielder if Caicedo leaves. And, for me, he can leave. We need another midfielder with the same characteristics, the same importance. In the Premier League, you know better than me, in midfield positions, sometimes you need more kilogrammes, more impact.”
Mahmoud Dahoud started in midfield against the Hatters and impressed with his range of passing.
Roberto De Zerbi said: “Dahoud is a great player for us because he is specific for our idea of football, for our style of play. But I think we lost different characteristics. Dahoud is different to Moises Caicedo.”
