What if the NBA Raised the Foul Limits?

Nov 18, 2013; Los Angeles, CA, USA; Los Angeles Clippers power forward Blake Griffin (32) gets up close as he defends Memphis Grizzlies power forward Zach Randolph (50) during first half action at Staples Center. Mandatory Credit: Robert Hanashiro-USA TODAY Sports

One of the most annoying things in an NBA game, especially a big playoff one, is when a superstar picks up a bogus foul call that puts the team over the foul limit and hands the opponent two free throws (which averages out to about 1.5 additional points), or when that superstar is forced to sit for an extended period of time. The NBA is a star-driven league, and most playoff teams rely on their best player (or best pair of players) to be on the floor as much as they possibly can, because without them the team’s production craters. Even the most balanced team-oriented teams crumble in those minutes. The Warriors are -17.8 points worse without Curry per 100 possessions. Clippers without Chris Paul, -16.7. Zach Randolph, -13.4. Big men in particular are vulnerable, as they generate more fouls and in are usually in worse positions to avoid them without giving out free points near the rim.

Teams can weather these storms to different degrees of success by contorting their lineups, but even then as a fan, it sucks. No one wants to see their favorite player sit on the bench in the most crucial moments of the year.

The Western Conference this season, may suffer the blunt of this. The Warriors can win 68 games and play the Kevin Durant and Russell Westbrook in the first round (if they make it in). Take Kevin Durant out of that match-up for 18 minutes he could have played and that may be it. The margin of error is nothing, and anyone can beat anyone. Statistically, most of the first round match-ups will basically be a coin toss.

We all know it when we see it — a player being taken out of the game unjustly because of a ticky-tack foul.  And it takes away from the enjoyment of the game.

Based on relative team strength (assuming neutral ground), the chart below depicts an estimation of win probabilities in NBA games when compared to expected point differentials (should look like a sports book’s spread vs. money-line calculation).

Expected Point Differential of a game vs. Winning Percentage.

The model isn’t exactly linear, but the first point is around 1 percent, the second 2 percent and the third 4 percent. To illustrate this, the expected outcome of a Washington Wizards and Atlanta Hawks game would be around three points, giving the Hawks a win probability of approximately 57-58 percent.

There are multiple ways bad or 50/50 calls can impact this result — when over the limit or on a shooting opportunity and you reward the opponent two free throws for an average of 1.5 points. And-1’s which add 0.75 points.  For a star player that is supposed to play 40 minutes in a game, but is limited to 28 because of foul trouble, he misses a quarter of the game’s possessions. In a league average 93.8 possession game, if the team is 15 points per 100 possessions worse without the star player, amounts to a -3.5 point loss, decreasing the winning percentage by somewhere around 10 percent.

These effects are likely to accumulate against or for one of the teams, but even if they evened out over a seven game series, a single foul call can strike an impact.

It’s hard to quantify how many 50/50 or blown calls there are in a game (although a certain owner in Dallas may have done the exercise), but what can be looked at are odds of players hitting foul threshold that force a coach to bench him. Two in the first quarter, three by second quarter etc, and how estimating how many minutes players are expected to sit due to foul trouble.

Fouls per 36 minutes by height in the NBA during the 2013-14 regular season.

Foul rates per-36 minutes double from a bit above 2.0 to 4.5 from the shortest to the tallest players in the NBA, and centers are over twice as likely to foul out of a game than guards. Expecting big men to play 40 minutes without getting into foul trouble is difficult, not only because on average they close to it already on a per-minute, but because of variance in how many fouls they commit. In a sense, it takes just a small push in the wrong direction to take a big man over the edge. The problem isn’t just fouling six times, but reaching those foul thresholds.

Take Blake Griffin for example, who fouls conservatively for his size. During the 2013-14 season Griffin averaged only 3.3 fouls per-36 minutes. In 80 games Griffin fouled out “only” four times, but hit five fouls an additional 15 times. That means at least in 19-of-80, a quarter of the time, Griffin was in foul trouble at the very least once in the game. By that rate, Griffin would expect to be in foul trouble in 1.66 games in a seven-game series, even without adjusting to increased minutes and, perhaps, a physical style of play (considering he might get to play Zach Randolph again this post-season). And based on Griffin’s foul variance he can expect to be in foul trouble between 3% of the time just in the first six minutes of the first quarter.

Teams committed 20.7 fouls per game last season, 5.17 per quarter. A few of those are offensive fouls that don’t count against the team foul limit, but still, a team can be expected to be in the penalty at some point in half of all quarters played.

The dilemma here is, does the punishment fit the crime? Title contenders need every inch of production they can get from their stars. Back during their 2011 title run, the Mavericks fell off a cliff every time Dirk was off the floor. They were a ridiculous 18.7 points worse and the trickery Rick Carlisle had to go through just to give him a spot of rest every now and then was a story line onto itself. Does the NBA punish fouling too much, if Blake Griffin who doesn’t even foul as much as many of his big-man star counterparts, is expected to be dealing with foul troubles that Doc Rivers has to re-work his entire rotation around in a quarter of the Clippers’ playoff games?

It’s possible that increasing the foul limit to to just seven personal fouls and/or move the bonus rules to the sixth foul could be a good change, or at the very least something that’s worth a serious look. Teams would shoot fewer free throws as a result of some weird back court fouls when in the penalty and players would have more lee-way when it comes to playing aggressive. To take a step back, the concept of “foul trouble” being a huge part of a fast-paced and fun game where the object is to throw a ball into a basket more often than the opposing team seems a bit arbitrary, even if that’s the way it’s always been done.

Increasing the foul limits would likely also award good defenses. The play-by-play data could be too noisy to extrapolate this fact from but when I watch a game I sometimes get annoyed when a team plays a stifling lock down defense for the first eight minutes of the quarter, but picks up two quick fouls on some scrums that could go either way or perhaps shouldn’t be called, and lose a much of the advantage they gained because the opponent gets one or two undeserved trips to the free throw line. Free throws also are the most boring part of the game, and it may be that the amount of free throws would decline slightly because fewer ‘cheap’ trips are gained.

An idea like this, if adapted or tested, would have ripple effects, both foreseeable and unforeseeable. For example, the value of fouls drawn would decrease slightly because it’s a bit more difficult to get into the penalty. There’s the concern that stoppages in the game would increase, as teams are able to play defense more aggressively. I’m not sure if that’s true if it was only a plus one foul increase per quarter, though it’s hard to tell. What it does is give teams just a little bit more rope for their star players to stay active within the game. Notably of course, both the team-limit and personal fouls, don’t have to be raised at the same time. And one could be more useful than the other.