Porte was third last year at the TdF, and I think he had never had similar results before. Does it mean the field was bad? I guess people will now start saying that Pogacar did not deserve his win because he didn't have to ride against Pogacar. Caruso is in the form of his life and this is one of the rare occasions where he can lead the team.
You will never find a GT where all the potential competitors are in good form and don't crash out. On paper this Giro had several people who either won or podium'ed in GTs: Bernal, Yates, Nibali, Carthy, Landa, Bardet. Many others like Martin and Buchmann have also had high finishes in the past. Then add the young promises: Vlasov, Almeida (who showed he deserved his 4th place of last year by riding very well except for stage four), Evenepoel, Sivakov, and Hindley (who was nowhere, but apparently quite ill). Ciccone and Caruso have been pleasant surprises; and there are other solid riders who were supposed to ride for GC, like Bennett.
I call this a stacked field, regardless of inevitable lack of form/luck/crashes.