NBA Metrics 101: Which NBA Playoff Myths Are Actually True?

Adam FromalNational NBA Featured ColumnistMay 9, 2017

NBA Metrics 101: Which NBA Playoff Myths Are Actually True?

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    Most NBA fans have heard the supposed truisms before. 

    Defense wins championships. Games slow down in the playoffs. Nerves keep players in check. Referees swallow their whistles and let the players play. The postseason is brutal for short guards. 

    But how many of those statements are actually true? 

    Thank goodness for numbers, because they're far more trustworthy than our own eyes in these situations. Confirmation bias can run rampant when evaluating the validity of potential myths, and working with a larger sample becomes much tougher. 

    With the help of a few simple calculations and comparisons, we can determine how many of these playoff myths hold water in 2017.

Shorter Rotations

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    NBA coaches can only trust their end-of-bench players so much when games truly count. As the theory goes, they'll play them in garbage time, but not when the stakes are higher. Rotations tend to contract during the playoffs, forcing teams to lean more heavily upon their star players and other key members, often at the expense of those who typically logged around a dozen minutes per game in the regular season. 

    Fortunately, this potential myth is easy to test. 

    Throughout the 2016-17 campaign, 405 players averaged at least 10 minutes per game—13.5 per team. Of course, that's a slight overestimate due to shifting rosters, as some contributors logged spot minutes during 10-day contracts and didn't truly serve as long-term rotation members. But that still gives us a baseline, and the playoff numbers are far different. 

    With second-round matchups nearing conclusions—only 151 players have recorded at least 10 minutes per outing. This time, that averages out to 9.4 players per postseason squad, and even that is an overestimate. These playoffs have featured so many blowouts that fringe rotation members have gotten on the court more frequently in end-of-game situations, so the truer number should be even lower. 

    Rotations are shrinking, and this is also made clear by looking at the workloads of the biggest names. During the regular season, 84 players (2.8 per team) averaged at least 30 minutes per game, and just 16 were north of 35 (0.5 per team). In the playoffs, those numbers have shifted to 62 (3.9 per team) and 30 (1.9 per team), respectively. 

    Key players receiving more run? Fewer end-of-rotation members consistently contributing? That seems like pretty clear-cut evidence of shorter rotations. 

    Verdict: Fact, Not Myth

Prevalence of Iso Ball

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    It's almost a natural byproduct of handing star players more minutes. Though nuanced sets are certainly prevalent on the biggest stages, plays more frequently devolve into one-on-one attacks. The sport's best are content to strut their stuff in the form of isolation attacks, singling out a defenders and doing their darnedest to embarrass them en route to the hoop. 

    We've seen Stephen Curry dancing around with the ball before knocking down a pull-up jumper. We've all witnessed Kyrie Irving flashing his ball-handling wizardry. We've seen LeBron James bully his way to the hoop for a physical finish. And despite the second-round elimination, no one has been better in isolation than DeMar DeRozan this postseason. 

    Only James Harden (61) has used more iso possessions than DeRozan's 59. But while the bearded guard's 1.13 points per possession leave him in the 76th percentile, his Toronto counterpart's 1.32 put him in the 97th percentile. To find the next player in the top 10 percent, we must travel down to Dennis Schroder, who accomplished the feat with the No. 16 possession tally—a mere 20. 

    But while standouts certainly exist, does this potential myth hold merit?

    With 59 postseason games in the books, the NBA as a whole has run 1141 isolation plays (19.3 per game). Based on team possession data, 9.21 percent of playoff action has fallen into this category, for an average of 0.911 points per possession. 

    During the regular season, the Association tallied 19,830 isolation plays over the course of 1,230 games (16.1 per game). That means 7.43 percent of the overall possessions could be classified as isolation sets, and they produced 0.882 points per possession. 

    Yes, the league is getting more isolation-heavy in the playoffs, but still not with enough efficiency to justify the volume gains. 

    Verdict: Fact, Not Myth

The Game Slows

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    It hasn't helped the Utah Jazz in their quest to end the Golden State Warriors' reign of terror over the Western Conference, but they're the model team for postseason pace. They always seek to slow down the tempo and force the opposition to fight through their oft-impenetrable half-court defense.

    All in all, games are supposed to grind to a painstakingly low pace during the playoffs. Each possession supposedly matters more, as teams are less likely to up the tempo and run the risk of making careless mistakes.

    But does that truly happen in the modern pace-and-space era? 

    The average team's regular-season pace stood at 96.4 possessions per 48 minutes in 2016-17, and it's fallen to 94.16 during the playoffs, based on calculating a weighted average. But the answer can't be as simple as that, since pace is directly dependent on the teams in action. The league's two fastest teams (Phoenix Suns and Brooklyn Nets), as well as six of the top 10, fell in the lottery this year. 

    Pace has fallen for 12 of the league's 16 postseason teams this year: 

    TeamRegular Season PacePostseason PaceDifference
    Atlanta Hawks97.498.41.0 Faster
    Boston Celtics96.893.83.0 Slower
    Chicago Bulls95.392.13.2 Slower
    Cleveland Cavaliers96.295.90.3 Slower
    Golden State Warriors99.899.20.6 Slower
    Houston Rockets100.097.72.3 Slower
    Indiana Pacers95.994.81.1 Slower
    Los Angeles Clippers96.189.86.3 Slower
    Memphis Grizzlies92.385.86.5 Slower
    Milwaukee Bucks94.590.54.0 Slower
    Oklahoma City Thunder 97.898.6 0.8 Faster 
    Portland Trail Blazers 96.7102.3 5.6 Faster 
    San Antonio Spurs94.290.14.1 Slower
    Toronto Raptors94.793.11.6 Slower
    Utah Jazz91.691.40.2 Slower
    Washington Wizards97.397.60.3 Faster

    The Atlanta Hawks and Washington Wizards attempted to run each other to death during the opening round, while both the Oklahoma City Thunder and Portland Trail Blazers fell victim to teams that typically play much faster. Ceding stylistic advantages is rarely a good idea, and it shouldn't be surprising that each of the latter two squads lost in the first round. 

    Verdict: Fact, Not Myth

Nerve-Wracking Experiences

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    Nerves are supposed to matter. 

    The pressure gauge is turned way up during the playoffs. Players sweat more. They feel the import of every situation, knowing their legacies are on the line. Each moment is more grueling, since one mistake could lead to early elimination and whisk away the Larry O'Brien Trophy. 

    Maybe. 

    There's also a chance players don't even feel the pressure, since they're so used to these situations. Every NBA player has felt the stakes rise at some point during his basketball career, and ramping it up further might not actually impact anyone's performance.

    To look at this objectively, we'll turn to free throws. As Tobias J. Moskowitz and L. Jon Wertheim explained in the book Scorecasting while using shots from the stripe to analyze home-court advantage, those are the most isolated and telling events in basketball: 

    "Free throws are an isolated interaction between one player—the shooter—and the crowd that is trying to distract and heckle him. Also, all free-throw shots are standardized; they are taken from the same distance of 15 feet at a basket standing 10 feet high, regardless of where the game is played. 

    "Over the last two decades in the NBA, including more than 23,000 games, the free-throw percentage of visiting teams is 75.9 percent and that of the home teams is...75.9 percent—identical even to the right of the decimal point. Are these shooting percentages any different at different points in the game, say, during the fourth quarter or in overtime, when the score is tied? No. Even in close games, when home fans are trying their hardest to distract the opponents and exhort the home team, the percentages are identical."

    The same theory holds true here, indicating that nerves might actually not matter too much during the postseason.

    Teams shot 77.2 percent from the line during the regular season, and that percentage has actually risen to 77.7 percent in the playoffs. During clutch situations in the postseason—defined by NBA.com as the last five minutes of games featuring a margin no larger than five points—the percentage sits at 75.6 percent. During the larger sample that is the fourth quarter, we're looking at 75.2 percent

    Of course, there are plenty of confounding factors here: the quality of players, for example. But none are bigger than the size of the sample, since even four additional makes would push the clutch percentage above the regular-season mark, and we've seen more than a few intentional misses in late-game situations. 

    Either way, there's not nearly enough of a dip to indicate players are succumbing to pressure in this most isolated of events. 

    Verdict: Myth Busted

Tough Offensive Luck for Short Point Guards

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    When games slow down (confirmed) and whistles get swallowed (more on this shortly), smaller players may not benefit. It's tough enough for them to thrive during the regular season when working against the many larger bodies offered by the NBA, but it may be downright impossible when their aggressive, contact-seeking bursts to the hoop aren't rewarded. 

    We're not talking about guards sized like Stephen Curry, whose 6'3" frame allows him to keep shooting over outstretched arms. But do players such as Chris Paul (6'0") and Isaiah Thomas (5'9") actually regress offensively during the league's second season? 

    Over the last decade, 21 different players, combining for 85 individual seasons, have qualified for the minutes leaderboard while standing no taller than 6'0". Forty-one went on to record at least 50 minutes during the playoffs that same year.

    Of those 41, just 12 managed to post a higher offensive box plus/minus (OBPM) during the playoffs than the regular season (29.3 percent). But that's not enough evidence that play dips for smaller guards, since we don't have an established baseline for bigger players. What if they also see their levels decline? 

    During the same decade, 378 guards 6'1" or taller have qualified for the minutes leaderboard during the regular season and then logged no fewer than 50 playoff minutes in the ensuing postseason. Of them, 117 posted higher OBPMs during the most important part of the year (31 percent). Diving even deeper, 762 players listed as swingmen, forwards or centers met the same set of criteria, and 241 saw their OBPMs improve (31.6 percent). 

    Using best-fit linear regressions for each grouping, we can estimate expected postseason OBPMs based on regular-season marks, and the differences there are most instructive of all: 

    Regular-Season OBPMExpected Playoff OBPM for Short GuardsExpected Playoff OBPM for Tall GuardsExpected Playoff OBPM for Non-Guards
    0.0minus-1.5minus-1.1minus-1.3
    2.00.40.50.4
    5.03.12.92.8
    10.07.77.07.0

    As it turns out, the playoffs don't cause short guards to decline by more precipitous amounts. It's harder for everyone to play efficient offense, and there's little difference between the three overarching player classifications. 

    Verdict: Myth Busted

Time for Fewer Whistles

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    Referees are supposed to swallow their whistles during the playoffs. Allegedly.

    Maybe they're trying to protect star players, ensuring they don't foul out of the proceedings or find themselves relegated to the bench to avoid that dreaded sixth call. Perhaps they're hoping to promote the flow of a game. Maybe they're just conditioned to allow more physicality when better teams are competing. 

    But the reasoning is of secondary importance. What's most crucial is figuring out if this whistle-swallowing is a legitimate trend. 

    During the 2016-17 regular season, the average team was called for 19.9 personal fouls per game. That number has actually gone up to 20.6 throughout the playoffs' first two rounds, though this isn't a new development:

    Fouls per Game2016-172015-162014-152013-142012-132011-12
    Regular Season19.920.320.220.719.819.6
    Playoffs20.621.121.922.022.221.2

    During each of the last six years, playoff games have featured more personal fouls per contest. To break the trend, you have to go all the way back to 2006-07, when the number dipped from 22.22 in the regular season to 22.17 in the playoffs. 

    So what gives us the illusion that referees are more hesitant to call violations? Could it be a specific play type warping our perception? If that's the case, drives are the most obvious place to look, given the proliferation of contact when players are bursting toward the hoop for contested finishes. 

    This year, teams have drawn fouls on 13.92 percent of their playoff drives—barely up from 13.9 percent through the first 82 games. Last year? After 13.76 percent of regular-season drives drew whistles, 14.22 percent did in the postseason. 

    Maybe our brains really are just tricking us. 

    Verdict: Myth Busted

Defense Wins Championships

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    Now, let's turn to the granddaddy of them all. 

    No one has ever played competitive sports without hearing that defense wins championships. That saying is always treated as a truism, meant to inspire players to compete on the less glamorous end when doing so isn't always rewarded. 

    I took an in-depth look at the validity of the saying back in 2014 and found it was partially true. Defense does win championships...but so too does offense. It's almost impossible to thrive without enjoying beneficial play on both ends, and neither one stands out as significantly more important. 

    That hasn't changed; at least, it hasn't changed in favor of defense. 

    From the 2015 playoffs through the present postseason, 39 series have drawn to conclusions. Of them, the teams boasting superior offensive ratings during the regular season have gone 31-8. Superior defensive ratings, meanwhile, have led to a 21-18 record. 

    Granted, teams sometimes change their levels of play during the postseason; LeBron James and the Cleveland Cavaliers have notoriously focused on flipping the switch as soon as they've finished their regular season. But these records are still telling, especially since the 2017 playoffs have consistently featured offensive superiority trumping any sort of defensive advantage—the Utah Jazz's first-round victory over the injured Los Angeles Clippers serving as the lone exception. 

    Throughout NBA history, there's little evidence defense is substantially more important than offense in the quest for titles. Now, recent shifts toward even more three-point shooting have made scoring prowess correspondingly more crucial. 

    Championship-winning teams will usually function as two-way juggernauts. But in 2017, "offense wins championships" is a more accurate statement than the opposite claim, even if both are technically true. 

    Verdict: Myth Kind of Busted

    Adam Fromal covers the NBA for Bleacher Report. Follow him on Twitter: @fromal09

    Unless otherwise indicated, all stats from Basketball ReferenceNBA.comESPN.com or NBA Math and accurate heading into games Monday, May 8.