Nylon Calculus: Steve Kerr coaches like a role player

He bobbled it, he dropped it – but in the end, Quinn Cook did exactly what Steve Kerr wanted him to do – he hoisted it.

It was the final minute of a critical Game 5, with the Western Conference Finals knotted up at two games apiece between the Golden State Warriors and the Houston Rockets. The defending champions were trailing by a point after once again pissing away a fourth-quarter lead. As the seconds ticked down, each Houston defender was keyed-in on one of the four Golden State All Stars, leaving Cook – a G-League call-up from the end of the bench – standing all alone with the ball in his hands and a chance to decide the Warriors fate.

“He’s got guts” Kerr said. “The biggest thing in the NBA – the only regret you should have is if you don’t shoot a shot.”

Of course, two decades earlier, it was Kerr, also a diminutive reserve point guard, who had the guts to shoot his own shot in a pivotal playoff moment. Kerr MADE his shot and, in doing so, won his Bulls a championship. The experience left an indelible mark on Kerr and, now, as an NBA coach, he expects his role players to shine in those big moments, just like he did.

Kerr’s enduring trust in his bench – at times celebrated, at times derided – is a fundamental tenet of his coaching philosophy.

Strength in numbers

Kerr brought big changes to Golden State when he debuted as the coach of the team during the 2014-15 season, chief among them was his decision to play his stars a lot less than his predecessor, Mark Jackson, had done. He dropped Stephen Curry’s playing time from 36.5 to 32.7 minutes per game. Likewise, Klay Thompson’s workload was dialed back from 35.4 to 31.9 minutes per game. Veteran wing Andre Iguodala experienced the biggest reduction in minutes played per game, with a decrease from 32.4 to 26.9. And all of that extra time, of course, was diverted to role players.

We can quantify the way that Kerr spreads his minutes around by borrowing a metric from the world of finance called the Herfindahl-Hirschman Index. HHI is a way to characterize “market concentration”, that is, it’s a way to measure how close a market is to being monopolized by a single firm. To calculate HHI, you just find the market share from each firm, square each percentage, and then sum them all up. To find an analogous “lineup density” we’ll just use MINUTE shares instead of market shares and individual PLAYERS instead of competing firms.

In the chart below, you can see Kerr’s impact on the Warriors lineup density: it dropped from an average of 12.4 in 2013-14 to 11.0 during the 2014-15 regular season. The change can be exemplified by considering some of the outlier HHI games from before and during Kerr’s time.

Both of the games featured above were impacted by injuries to star players as Curry sat out of the November 2013 matchup with the Grizzlies and Kevin Durant missed the game against the Bulls in November 2017. Whereas Coach Jackson leaned even more heavily on his remaining starters in the absence of Curry in 2013 (playing each one for more than 40 minutes, HHI=15.9), Coach Kerr distributed Durant’s minutes to a variety of role players in 2017 (nobody played more than 27 minutes, HHI=8.5).

“The biggest challenge of being a bench guy is keeping your confidence up, and one of the ways you can instill that confidence is by playing him once in a while,” Kerr told Connor Letourneau of SF Gate. “People might think I’m crazy with my rotations, but you can’t expect a guy to have confidence if you don’t play him for two or three weeks.”

To provide some context for this new metric, we can compare Golden State’s lineup density for the 2017-18 regular season to all the other teams who made the playoffs. We can look at some other, more conventional, measures of bench utilization, too.

Kerr has the Warriors near the top of this list as the team with the third-least concentrated lineup rotations among all playoff-eligible squads (HHI=10.8). Golden State is also one of a handful of teams who had at least a 40:60 split in the minute share between the bench and the starters. On average, Kerr played the most players per game – going 12 deep, on the regular.

“I think there’s something powerful about everybody playing,” Kerr said. “I learned that from Phil Jackson. If you remember in kind of the early days, early ’90s when the Bulls started winning titles, [he] had a lot of guys who would come off the bench…”

Echoing the theme that has become a Warrior’s mantra, Kerr continued: “there’s a strength that comes through that and a unity.” A Strength In Numbers.

In fact, Kerr’s Warriors have even more guys coming off the bench than Jackson’s Bulls did. The lowest lineup density that Kerr experienced in Chicago was during the 1994-95 season (mostly without Michael Jordan), when the Bulls achieved an HHI of 11.2.

Going deep, in the playoffs

Of course, it’s easy to get everybody in the game when you’re constantly blowing out your opponent, as the Warriors have often done during the last four regular seasons. But, what happens when push comes to shove? Has Kerr’s egalitarian philosophy of inclusion withstood the pressure cooker of the postseason?

Well, we can make some head-to-head comparisons of lineup density by playoff series using the charts below.

Overall, Kerr’s lineups have tended to be less concentrated than his opponents – even in the more competitive atmosphere of the playoffs (the orange lines tend to be below the gray ones, on average, by a margin of 0.5).

This trend has been especially apparent in specific matchups – against Cleveland in the 2015 finals, against the Blazers and Thunder in 2016, and against the Pelicans this year – in which the other team has had a shorter bench. Oh, and also in pretty much every game against the Houston Rockets during Kerr’s tenure.

The Spurs were the one opposing team who consistently relied more heavily on their bench than the Warriors, during their matchups in both the 2017 and 2018 playoffs.

Below is a list of the games in which the orange line drifted furthest below the gray line – the games where the Warriors went much deeper into their bench than the opposing team.

As you can see, the strategy hasn’t always paid immediate dividends. In fact, at times, Kerr’s rotation choices can feel downright nutty. For example, he turned to the rarely-used center/talisman Anderson Varejao for seven minutes in Game 6 of the 2016 finals (HHI differential of 2.6) and for eight more minutes in Game 7 when that didn’t work. Some members of Warriors Twitter may never let him live that down. Still, in the long run, there are undeniable benefits to running a team that shares the load.

The big payoff

Kerr’s special connection to his role players and his proclivity for keeping them involved in the action has a side benefit of protecting his team’s superstars from exhaustion and injury.

It’s pretty distasteful to point fingers when a player gets injured, but…Houston’s Chris Paul IS 33 years-old and he DID carry a heavy load during the first five games of the series – playing 37 minutes per game on an every-other-night schedule. Maybe fatigue WAS a contributing factor for his hamstring injury?

Despite being a dominant regular-season team, Houston was on the higher end of the spectrum for lineup concentration, with an HHI of 12.2. Maybe a more balanced minute distribution among the Rockets could have saved Paul from being sidelined for the last two games of his 2018 postseason?

Or maybe not. The Warriors certainly had their share of injuries this season, too, despite the lighter minute loads. Maybe the more salient contrast, then, is in how the two teams were able to deal with their injury situations during the series.

With Paul out and Luc Mbah a Moute limited, Rockets Coach Mike D’Antoni was forced to rely heavily on his five starters plus Gerald Green in Game 6 (HHI differential of 0.9). The result was a tired team and a second-half collapse. In Game 7, D’Antoni tried to work Rockets reserve Ryan Anderson back in the mix, but he struggled and looked uncomfortable in his limited opportunities. Again, the undermanned Houston roster (HHI differential of 1.0) seemed to lose their legs in the second half, shooting just 7-of-44 from the 3-point line, and they limped to the finish.

Next: Why are the Warriors so dominant in the 3rd quarter?

In contrast, with Andre Iguodala missing the last four games, Kerr embraced a number of new lineup combinations and gave several different role players a chance to contribute. Despite some inconsistent play, Kerr stuck with his young bigs Kevon Looney and Jordan Bell (21 and 17 minutes per game in the last four games, respectively) as well as the streaky Nick Young (12 minutes per game). He continued to trust veteran reserves Shaun Livingston (18 minutes per game) and (the briefly shelved) David West (9 minutes per game).

And, of course, Quinn Cook had his moments, too. He missed that last-minute shot in Game 5 and with it, his chance to vindicate Kerr’s “Strength in Numbers” philosophy. But he’ll have more chances in the finals and Kerr, undoubtedly, will be expecting him to make the next one.