Why do you say this like the Bucks didn't just beat a Nets team with Durant and Harden, where a number of the games were close, which Milwaukee won? Are you forgetting Game 7 where they had to come from behind in the final minutes to take the game to overtime where they had to "out execute"the Nets? Are you forgetting what Middleton and Jrue did down the stretch of that game? If they can beat Durant and Harden in close games why aren't they capable of doing it against Devin and CP3?
And I don't see why you're looking at this from an equation of Devin + CP3 vs. Giannis, when really it's Devin + CP3 vs. Giannis + Middleton + Jrue.