Zach Lowe, ESPN (http://espn.go.com/nba/story/_/id/14505051/transition-defense-left-offensive-rebounds-cutting-room-floor)

Brett Brown still remembers the mantra Gregg Popovich and his staff in San Antonio recited to warn perimeter players against chasing offensive rebounds.

“We don’t care if you get an offensive rebound in your entire life,” Brown says, laughing. “And we’d say it to them exactly like that.”

Popovich was among the first in a wave of coaches to order four or even all five players to run back on defense the moment a shot went up. Retreating prevents fast-break points and forces opposing offenses to work against both a set defense and the dwindling shot clock. That is the first step in quieting explosive opponents, and any tactic that ran counter to it — such as having too many guys crash the offensive glass — would be used only in tiny doses. It is almost orthodoxy in most of the NBA today: Offensive rebounding doesn’t matter, especially because it threatens the integrity of your defense.

“San Antonio set the model,” says Terry Stotts, the Blazers’ coach. “Offensive rebounding has never been a priority for us.”

Doc Rivers, Stan Van Gundy, Steve Clifford, Erik Spoelstra and Rick Carlisle are among the coaching giants who have (mostly) gone down the Pop path.

“Right now, everything is tilted toward transition defense,” Brown says. “We are all sheep.”

Players feel the shift too. “Years ago, every coach was looking for offensive rebounds,” says Luis Scola, Toronto’s starting power forward. “And now it’s so different, because coaches don’t want to give up transition points. That’s why players stopped doing it.”

The effect has crescendoed this season. Leaguewide, offenses have rebounded just 23.8 percent of misses, on pace to be the lowest overall mark in NBA history. On the flip side, the Spurs, Hornets and Cavs all have a chance to set the all-time record in defensive rebounding rate — a record Charlotte set just last season. “If you study the numbers,” Clifford says, “you find that offensive rebounding just isn’t important in winning big.”

He’s right in a literal sense, but there might be a chicken-and-egg thing going on. Does ignoring the offensive glass help teams win, or is it just a characteristic of most NBA teams — including those that win? Several teams, including recent versions of the Blazers and Pacers, have managed to dominate the offensive glass without sacrificing transition defense. Should more teams try to find that happy place?

“I do think some team is gonna turn the tables,” says Jeff Van Gundy. “You can play smaller, and get back on defense, and still pursue offensive rebounds. Someone is going to try to be different.”

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The historic drop-off goes beyond transition paranoia. Teams are playing more small ball, and asking their power forwards to shoot 3s — slotting good rebounders 25 feet from the rim. “You’re just so far away,” says Kris Humphries, who barely snags offensive boards now that the Wizards have turned him into a 3-point shooter. “It’s hard to run all the way in, and then run back on defense.” Kevin Love, Serge Ibaka, Scola and lots of other reinvented snipers could empathize.

Smaller teams also move faster; the league’s overall pace keeps jumping, and that fuels the fear that overeager offensive rebounding can turn every opposing offense into the Warriors.

The rise in 3-point attempts also has deflated offensive rebounding. More jumpers mean fewer shots at the rim — missed bunnies that produce the most offensive rebounds, in part because the shooter is often in good position to catch his own miss (i.e. The Carmelo). Long shots lead to long rebounds, per SportVU data, but not the sort offenses retrieve at a high rate.

Offensive rebounds are super-exciting! It would suck if all these trends, rising in lockstep, resulted in the gradual extinction of offensive rebounding beyond a few fluky bounces. Good news: Coaches are starting to wonder whether crash-phobia has gone too far.

“It’s something we’re all struggling with,” says Brad Stevens, the Celtics’ coach. “Teams all place a large focus on defensive rebounding. If that’s important, then offensive rebounding must be important, too.”

The difference between rebounding 23 percent and 30 percent of your own misses — what the league averaged not long ago — might amount to only two or three extra possessions each night, but in a close game, that could make a huge difference.

“There isn’t one coach who doesn’t put a high premium on defensive rebounding,” Stotts says. “But doing that, while ignoring offensive rebounding — that’s the paradox.”

Says Brown, simply: “There is a huge disconnect there.”

Fittingly, the very changes that appear to be phasing out offensive rebounding — 3s and small ball — are driving coaches to reconsider their approach to it. Kickout 3s immediately after an offensive rebound are among the very best shots in the game. Over the past two seasons, teams have shot about 39.5 percent — well above the league average — on 3s attempted one pass after an offensive rebound, per data from Vantage Sports supplied to ESPN.com. So far this season, teams have nailed about 39 percent of triples launched five or fewer seconds after an offensive rebound, per SportVU data provided to ESPN.com

“If you kick it out and get a 3, that has very powerful momentum,” says George Karl, the Kings’ coach.

“It’s just so deflating to defend for 23 seconds, give up a rebound, and then have it turn into a 3,” Stevens says. “It reminds you how big an impact offensive rebounds can have.”

If you can’t compete against a small-ball team on its terms, you might as well try to bully it — especially if it switches a lot on defense, leaving smaller players on big guys at the end of possessions. “You have to punish those teams,” says Jason Kidd. “You have to get offensive rebounds.” This is what behemoth teams like the Jazz, with Rudy Gobert and Derrick Favors, are betting big on.

That is how an undermanned Cleveland team pushed the Warriors in last year’s NBA Finals — at least for most of the first five games. The game slows in the playoffs, and becomes about matchups. Offensive rebounding might emerge as a weapon against a specific opponent, but it’s hard to retrain a skill if you’ve just spent almost 100 games ignoring it. “When you’re facing the best teams in the playoffs, you need as many ways as possible to score,” Clifford says.

For at least a few games, last season’s Cavs showed that ultra-aggressive offensive rebounding can curb dangerous transition offenses. If a team needs extra bodies to protect against offensive rebounds, it can’t get out on the break as quickly. “We always felt like if we were putting pressure on opponents to box us out,” McMillan once told me of his old Portland teams, “then they couldn’t get out and run.”

This is one area where the clichéd conflict between analytics experts and coaches is still happening. A lot of analytics staffers have pushed coaches to get more adventurous crashing the glass, only to find that coaches can’t stomach the risk. And in some cases, those coaches may be right.

It’s unclear whether ambitious offensive rebounding really hurts a team’s transition defense, but teams like McMillan’s Blazers and the 2012-14 bully-ball Pacers — teams that do both at elite levels — are rare. The top five offensive rebounding teams of the past seven seasons have ranked right around the league average in the best publicly available measures of transition defense: fast-break points allowed, opponent points per possession on transition chances, and the percentage of opponent shots that come in transition (via Synergy Sports). That’s not bad, but it’s also not good.

With new visual data from fancy SportVU cameras, teams can track this stuff in more sophisticated ways. They can record how many players are near the rim when a shot goes up; which of those players tries to get the rebound; who is good (and bad) at boxing out; and what happens when aggressive offensive rebounders whiff.

Teams keep most of their findings secret, but the wizards at Nylon Calculus use public rebounding data to track which offenses most often have players near the basket, in rebounding position, when someone jacks a shot. They call this “chase percentage,” and over the past two seasons, the top five chase teams have ranked around 19th or 20th overall in those same measures of transition defense. (This jibes with some of the non-public data I’ve seen.)

Crash and come up empty, as Rajon Rondo and Omri Casspi do on the possessions below, and you might pay a price — fast — at the other end:

At the same time, the paranoid offensive rebounding teams tend to be among the best at limiting fast-break points.

In other words: There may be real danger in banking too much on offensive rebounds. And that may be especially true for the best teams. Good teams have good offenses, and good offenses make almost half their shots. If the first shot is a decent bet to go in, perhaps the risk-reward calculus favors getting back on defense. This probably plays some role in explaining why good teams appear to avoid the offensive glass: because they’re good, not because offensive rebounding is on its face a bad thing.

It’s also unclear if extra scavenging for second chances is the reason some of these teams hemorrhage fast-break points. The Suns, Kings and Rockets of the past two seasons have all fallen into the category of teams that chase offensive boards and suffer for it on the other end. They also all have terrible habits. Houston’s floor balance has been awful all season; corner shooters just chill during James Harden drives, so that if he misses at the rim, four Houston players are below the foul line — a recipe for fast-break death. The Suns loiter around the paint. DeMarcus Cousins is constantly lollygagging in transition, and the Kings have been a mess for a decade.

Those three teams also play fast, and teams that push the break get into track meets that produce more transition points. Only the Sixers allow more fast-break points than the go-go Warriors, and no one accuses Golden State of reckless offensive rebounding. By the same token, teams that squash opponent fast breaks might do so more by playing slowly, rather than by punting the offensive glass. Or do they play at a slow pace precisely because they punt the offensive glass, and force opponents into a half-court game? Untangling all these effects from one another is really hard.

Every team has players with good instincts for crashing the glass. If you emphasize it, with clear teamwide rules, perhaps there are a few opportunities every game waiting to be exploited. Hell, even the Spurs let Manu Ginobili and Kawhi Leonard slip inside when they sensed an opportunity. “We gave them a hall pass,” Brown says. “Even today, I give JaKarr Sampson a hall pass. I gave K.J. McDaniels one when he was here. And when I thought we were getting Andrew Wiggins, I was ready to rewrite my offensive rebounding rules.”

“That’s where we really miss Michael Kidd-Gilchrist,” Clifford says. “He has such a good feel for it.”

Brown is trying to teach Philly’s corner shooters to loop up toward the foul line when a teammate launches a 3-pointer, just in case a long rebound happens to carom there. Both Stotts and Frank Vogel encourage the same tactic. “With everyone shooting 3s, you might be able to pick up some cheap points,” Brown says.

The best modern offenses organically manufacture offensive rebounding opportunities they might be passing over now. Whip the ball side to side through two or three pick-and-rolls, and the defense will be scrambled by the time you shoot. Defenders will have rotated into mismatches, sprinted way outside to fly at shooters, or drifted into space after running around. Watch how one backdoor cut from Garrett Temple leaves Kelly Oubre free for a putback dunk:

Or how Amir Johnson reads that Brook Lopez has leaped out to challenge a jumper, leaving only one Brooklyn big man to box out both Johnson and Jared Sullinger — a golden chance to pounce:

On pick-and-rolls, most defenses shift away from shooters on the weak side to clog up the paint. Smart cutters like Dwyane Wade slice backdoor for layups in that moment when their defender sneaks toward the ball. The same cut can put a little guy in prime offensive rebounding position; the Rockets, for instance, let Patrick Beverley skulk for these sorts of offensive rebounds. “I respect the counterargument about getting back on defense,” says Daryl Morey, the Houston GM. “But when you have Patrick Beverley, it would be a mistake not to use his offensive rebounding.”

Adds Van Gundy: “No one boxes out those little guys, anyway.”

Even some of the league’s greediest rebounders don’t box out. Pick the right spot, and you can sneak around DeAndre Jordan.

No one knows the right balance, only that it varies by team, opponent and specific personnel. The ideal scenario is probably to have one big guy so unstoppable on the glass, he single-handedly props up his team’s offensive rebounding — leaving four teammates to run back on defense. This is the Andre Drummond archetype.

“That is really the best of both worlds,” Van Gundy says.

The Mavs are using Zaza Pachulia as their ground-bound, less effective Drummond; when Pachulia is in the game, he is the only Mav allowed to pursue offensive boards, he says.

Not every team can have a Drummond, and some teams are clearly leaving points on the board. It’s insane that New Orleans ranks at the very bottom in offensive rebounding rate with Tyreke Evans rumbling to the rim, and both Anthony Davis and Omer Asik lurking. The Clippers rank dead last in chase percentage, but a robust No. 3 in securing offensive rebounds when they actually try, per Nylon Calculus. That dichotomy suggests they should let Jordan and Blake Griffin hop for a few more.

“I mean, a lot of times, Jordan isn’t even going to the boards,” Van Gundy says.

The Clippers sported the league’s No. 1 offense in each of the past two seasons, so Rivers wasn’t giving up much. But they’re down to No. 4 this season, far behind both Golden State and Oklahoma City, and they can’t afford to leave any points on the table in the playoffs against the best in the West.

Bad teams have even more incentive to crash hard; they miss more often than good teams! Brown knows that, and is working to get the Sixers out of the bottom 10 in offensive rebounding rate. He’s pushing both Jahlil Okafor and Nerlens Noel to chase more rebounds, and he thinks defenses are more vulnerable on free throw misses than we might expect. Brown says too many players go through the motions of rebounding when a teammate is on the line, bumping lightly into the defender in front of them. “I call them back-riders,” Brown says. “And it’s just B.S.”

When Brown was coaching in Australia years ago, Mike Dunlap, the former Bobcats head coach, shook up the Aussie league by sending four of his guys to the offensive glass on almost every possession. “He literally changed the whole league,” Brown remembers. “And maybe someone will do that here. We are all so caught up in transition defense right now.”

Van Gundy agrees. “Everyone is always looking for that little difference that can help you win,” he says. “And it’s good for the league when teams play differently.”