Is Boston’s “Best Five” lineup really their best lineup?

With the return of Gordon Hayward, Brad Stevens unleashed the Boston Celtics so-called “Best Five” lineup. This group features Boston’s best five players of Hayward, Jaylen Brown, Marcus Smart, Jayson Tatum and Kemba Walker. While this lineup was terrific during the Celtics Game 3 victory over the Miami Heat, the question remains: Is this Boston’s best lineup?

Following Game 3, Stevens said it was a lineup he rarely got to deploy during the regular season because one of the five players were almost always unavailable. In all, the Best Five grouping logged just 18 minutes together over seven regular season games.

And it was a disaster.

In those 18 minutes, the Celtics were outscored by six points. That was one of Boston’s few lineup combinations that logged more than 10 total minutes to be outscored. Most of the other combinations featured two or more bench players.

Another way to look at it: The Celtics net rating in those 18 minutes? -21.5. Boston had an offensive rating of just 97.4 and a defensive rating of 118.9. Both of those marks are among the worst of all the lineups that played at least 10 minutes together in the regular season.

So, why did Stevens have the faith to turn to it during key moments in a must-win game? There are a few answers to that question.

First, 18 minutes over seven games is an extremely small sample size. As bad as it was, that’s not enough to make real judgements on.

Second, the Heat personnel allows the Celtics to get away with this grouping, despite their relative lack of size. Miami only plays on big at a time and that’s usually Bam Adebayo. As good as Adebayo is, Brown has had some level of success defending him. In addition, Brown, Hayward, Smart and Tatum can switch everything in this lineup. That keeps them connected to the Heat shooters And, because Boston is small and quick, they can scramble Walker out of bad matchups easier than with a slower-footed big on the floor.

Lastly, and this one is hard to define by the eye-test or the numbers, Stevens trusts in his best players to play the best. Stevens wasn’t going to let some poor play in limited regular season minutes dissuade him from going to his best players when he needed them most.

Thus far, the Best Five group (which needs a better nickname because Best Five is pretty blah!) has played only seven minutes over two games. Boston used it briefly in Game 1 of the first around against the Philadelphia 76ers and then to close each half of Game 3 against the Heat. In those seven minutes, the Celtics are +13. Their offensive rating is an absurd 162.5 and the defensive rating is an even more preposterous 76.5, for a net rating of +86.

As we look a little deeper into the numbers, some trends start to emerge. Not only about the Best Five lineup, but about some other lineups as well.

In the regular season, the Celtics most-used lineup was their regular starting five of Brown, Hayward, Tatum, Walker and Daniel Theis. That group was very good, as far as starting lineups go. They were +52 in 262 minutes over 23 games. They had an offensive rating of 115.9, which is right behind the Dallas Mavericks NBA-best 116.7. The Celtics defensive rating with their regular starters was 105.3, which is slightly better than their fourth-best overall defensive rating. The net rating for the starters was a very healthy +10.6.

That lineup was clearly very good offensively, and that’s backed up by 49.7% shooting from the field, including 39.8% from behind the arc. The team’s assist percentage with the starting group was a robust 61.6%, meaning they had the ball moving.

With Hayward out, the Celtics turned to Marcus Smart in the starting group. It’s no knock on Smart, but the regular playoff starters of Smart, Brown, Tatum, Theis and Walker aren’t quite as good as the regular season starters. The competition is simply better in the postseason. That group, with Smart in there, has played in all 14 playoff games against good teams. There’s no New York Knicks to get fat on in the postseason.

In the 14 playoff games, Boston has played their starters 218 minutes. They are +7, but the offense drops off considerably, while the defense is only slightly better. The offensive rating and defensive ratings pinch closer together at 108.3 and 104.7 respectively, for a net rating of +3.6. Still good, but hardly dominant.

What do we see with this group? They don’t shoot it as well, as they are 44.7% overall and just 31.2% from behind the arc. They also play at a slower pace, which is likely influenced by the overall slower pace of the playoffs versus the regular season. Less offense plus slower pace equals closer games.

Because Hayward has been out, the regular season starters have totaled just 17 minutes in two postseason games. But, like in the regular season, the results have been excellent. Boston is +13 during that time and boasts a silly 139.4 offensive rating against a terrific even-100 defensive rating. The ball flies around with a 73.7% assist rate. That helps the Celtics to 55.9% shooting, 45.5% from behind the arc.

All in all, it looks like the regular season starting five has carried over their success to the postseason, despite some small sample sizes.

Oddly enough, the best lineup in the postseason with at least 20 minutes together is Brown, Smart, Tatum, Walker and Enes Kanter. That grouping +15 in 20 minutes. They have an offensive rating 140, and a surprisingly (considering Kanter is on the floor) competitive defensive rating of 105.1. This lineup logged most of their minutes against Joel Embiid and the 76ers, with a small handful coming in Games 2 and 3 against the Heat.

Overall, we can conclude a few things from looking at the lineup data. First, the best lineup the Celtics have seems to be their regular season starting five of Walker, Brown, Hayward, Tatum and Theis. Against Miami, because Boston needs Smart to defend Goran Dragic, it’s fine to stick with the playoff starting five. But even if Stevens doesn’t go back to the regular season group to start, they should still plenty of minutes together.

Second, the Celtics are better with Gordon Hayward on the floor. Every lineup with Hayward boasts better assist percentages, which matches the eye-test that the ball moves better with him out there. Those groups are all very dynamic offensively and more than competitive on defense. Hopefully this puts to rest any questions of Boston being better without Hayward, as nonsensical as they have always been.

Also, there is a place for Enes Kanter in the postseason. It’s probably not against pick-and-pop bigs like Serge Ibaka or Kelly Olynyk, or against crafty pick-and-roll ballhandlers like Goran Dragic, but there are spots. When Dragic is off the floor is the sweet spot. And, if Boston should advance, Kanter should have a role against either the Los Angeles Lakers or Denver Nuggets and their backup big men.

Finally, the Celtics are whole again. With Gordon Hayward available, it allows Brad Stevens to mix and match personnel. There aren’t very many styles Boston doesn’t have an answer for with some lineup combination. And, Stevens can finally play that Best Five group together to close each half with potentially game-changing results.