They're both doing well, but let's not get ahead of ourselves. Spina has played all of 3 games, and while he's been promising, that's a very small sample size. Berna put in a great performance against ATM, but he's also had his fair share of stinkers. It's not as if he is Mr. Consistency personified. You'd also be able to see that if you took off your biased Mama Italia glasses every once in a while.
As things stand, we are a team that harbors ambitions of competing for the CL year in year out. Selling Dybala for Chiesa and Zaniolo is a step in the wrong direction and a downgrade, regardless of what your Azzurrri heart might be telling you.
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Also, I wasn't saying sell without getting replacements. We obviously need a 2nd keeper, but I'm sure a cheaper option can do the job just as well as Perin. He's only played all of 5 games this season?!
Rugani is a luxury and not a necessity, especially with Romero coming in. Add another defender (De Ligt) and we're set in defense for years to come.
We have Cancelo, Spina, and De Sciglio. Sandro might be problematic to replace, but not this version of Sandro.
Costa has been absent for long stretches, and we've done well without him. Also, Cuads will be back next season. Having said that, bringing in Chiesa and Zaniolo helps with the depth issue.