The final results are in, at least for this series. The most used line up was:
A. Horford - M. Smart - J. Brown - J. Tatum - D. White 82 min +17
That isn't necessarily the best line up though. It is hard to say exactly what the best line up was, what metric to use.
The most impactful player was clearly Al Horford. He ended up at +60 overall. RWill was -9 overall. Grant was -6 (in only 3 games). Al was the big that impacted the game all series.
And he got so much criticism in that series.
I thought Horford played good defense throughout particularly on those switches with Trae Young. How many centers in the league would defend Trae better when left alone on an island against Trae? A player as quick and as skilled as Trae? Hardly any. Only a small number could defend Trae as well as Horford did.
The expectations for what a center should be able to do in one-on-ones defensively against Trae were all out of whack. Horford did his job and did it well against Trae.
Any issues with Horford vs Trae were ones of coaching strategy in choosing to accept so many one-on-ones with Trae instead of using alternate strategies. That is not Horford's fault. That is the coach's fault.
Horford played really well on defense in that series. He was quiet on offense but not bad because of the value of his passing and pulling the opponent bigs out of the pain which helped ease his reluctance to shoot and so-so shooting numbers in the series.