You play your best players. Our best players were mostly wings, plus that is today's basketball. We also played 2 big lineups.
You don't play guys just because they are big. The Pelicans played big with two of the best centers in the game,didnt even reach playoffs. The warriors with a 6-8 dude playing cneter won 3 championships. This is a different era where skill>height.
Yet Baynes and Horford together were one of our best defensive options and allowed us to hang with Philly. So it is not as simple, as you make it out to be. The trouble is we don't nor have we had enough good bigs aside from Al. Al is a two way player, Baynes was not. We also don't have the shooters to offset the bigs like Golden State has on their team. Durant also had plenty of size, and is a great deal bigger than 6-8.
So once, again a generalization, is shown to be as full as holes as Swiss Cheese.
I would also point out that the Warriors can go big most of that era if they needed too. Small ball was not their only option. That is the problem with management here, they do not see as a tactical option in a game but rather a foundation to build the team on. Against Big teams like the Bucks we were exposed. A team ought to have options for both and we are going to see that this year because we don't have Al did a lot of things to mitigate this weakness.
When that 6'8 player has a rare combination of length, motor, strength and skill, his lack of size is mitigated at the center spot. They also have a 6'7 SG, a 6'9 SF/PF and a 7'0 freak who can play all three frontcourt spots in a pinch, as well as the greatest shooter of all time to bolster their offense. We don't have that combination of offensive firepower and defensive versatility, and we played three guard lineups when Golden State played one guard with 3 wings and 1 forward/center as "going small". You don't have to play huge, but you can't play tiny either.
I know, it was a gross simplification, and your post, which I noted after posting mine, Pointed those things out admirably.