This is a red herring, Hoori, because you present an "
assume a spherical chicken" problem.
You play your Coppa squad not because that's your best squad to win. You play it because you're resting some of your regular starters for the Serie A championship.
The Serie A championship was over two weeks prior. Conte had a full two weeks to properly rest players for the next competitive match they had on the calendar.
If Conte enters the Coppa final with his Coppa squad, with the Scudetto in the bag, he's fielding a substandard team -- one that Napoli surely did not field given their CL squad and all.
Extending statistics for previous Coppa matches is irrelevant, because Serie A was already effectively over two weeks before the match.