In the three seasons since they both signed in Brooklyn, there have been 226 regular season games. Of those 226 regular season games, KD has played in 90 of them, or 39.8% of the games. With that in mind it doesn't really matter that the Nets are 59-31 (.656) when KD plays. Kyrie has played in 103 games, or 45.6% of the games. It also doesn't matter that they are 58-45 (.563) when Kyrie plays. They have played together in just 44 games total, which is just 19.5% of the time. So it absolutely doesn't matter that the Nets are 27-17 (.614) when they both play. They have not been available for various reasons and it has devastated the franchise.
The first year was understandable, given KD's injury in the 2019 NBA Finals it was known that he wasn't going to play in the 19-20 season. If you cut out that season, KD has played in 90 out of 154 games, which is 58.4%. That's still a lot of missed time.
Kyrie's situation is far less forgiving than Durant's, due to him missing huge chunks of time for personal/avoidable reasons and pure selfishness. He has, on multiple occasions, valued other things over basketball and his commitment to his maximum NBA contract. The fact is he has never given the Nets his full commitment in the time he's been there. He's only done it on his own time, and on his own terms. He can leave on a whim and it's not that big of a deal when they lose. He didn't seem very upset about them losing last night.
The fact is in three seasons since they both signed in Brooklyn, the Nets are 127-99 (.562) in the regular season, and have lost three of the four playoff series that they've participated in. They have yet to reach even the Conference Finals, and they are the first team in over 35 years to be swept in the first round when they entered the season as the Vegas odds title favorites.
The James Harden/Ben Simmons garbage only makes it worse, and I believe there is a good chance they could trade Simmons this summer. It would be fitting if Simmons never played a game for the Nets.