How Derrick Rose’s Injury Affects The NBA Playoffs

• 2 comments - NBA - posted by Austin Link on May 1, 2012

Usually the most important game of the NBA playoffs is the last one, but in 2012 it was the very first.

With one bad landing, reigning MVP Derrick Rose is now out until next year, leaving the overall #1 seed Bulls without their greatest offensive weapon.

Going in to the playoffs there were four serious contenders: Miami, Oklahoma City, San Antonio, and Chicago.  Without their only true star, the Bulls no longer seem to belong in that group.  The debate has shifted from whether they could be champions to whether they can make it out of the first couple rounds.

The Extent Of The Damage

A couple stats emerged after the injury that made things seem less bleak for Chicago.  Perhaps most surprising among them is that the Bulls beat their opponents by an average of 8.7 points with Rose, and that margin of victory only dropped to 7.5 points without them.  If losing Rose means just a 1.2 point hit to the Bulls rating, then a title is not out of the question.

However, is that 1.2 point value actually a good estimate of the impact of Rose? It seems a bit small, doesn’t it? Our predictive power ratings back up that intuition.

As part of our ratings we keep track of a “Game Score” for each game, which rates how a team would have fared against an average opponent.  By averaging the Games Scores over the contests Rose did or didn’t play in, we can tell that the Bulls were 9.4 points better than an average team with Rose, but only 4.9 points better without him. That’s a much larger difference of 4.5 points.

What about some other metrics?

Opponent-adjusted plus-minus, Offensive Rating, and Defensive Rating show Derrick Rose as about 10 points per 48 minutes better than CJ Watson.  Given their regular playing times, substituting Watson for Rose would make the Bulls about 7 points worse over the course of a game.  Of course, Watson doesn’t fill the same niche as Rose, so more shots end up going to Luol Deng, Carlos Boozer, and others. That reduces the effect a bit — probably enough that it roughly agrees with out 4.5-point estimate.

Vegas bookmakers put the value of Rose at around 3-4 points, which is also close to the 4.5 point difference predicted by raw Game Scores averages.

So why does looking at simple margin of victory seem to show the Bulls were only 1.2 points worse without without Rose?  It turns out that Chicago faced a significantly easier schedule while they were sans point guard.  With Rose playing, their average opponent rating was about equal to the Utah Jazz; without him, their opponents were roughly on par with the Minnesota Timberwolves.  That easier schedule may have lured Bulls fans into a false sense of security.

Simulating The Playoffs

We plugged this new knowledge about the impact of Rose’s injury into our NBA season projections to see how the numbers changed.

The projections currently give the Bulls a 30.6% chance of winning it all, but they don’t know about Rose’s ACL tear. When Chicago’s rating is docked to reflect his absence, the projections still show the Bulls with a 11.8% chance of winning the title.

So, not only is Chicago still technically favored to survive first two rounds (although barely at 51.2%), but they still have a decent shot at winning everything. But 4.5 points is quite a bit worse; why don’t their odds take more a hit?

The issue here is that the current ratings don’t see a full strength Derrick Rose; they use a Bulls rating that reflects Rose only playing 60% of the season.  If the projections used a full strength Bulls — the ones who played 9.4 points better than an average team — Chicago would become a juggernaut, winning the playoffs a whopping 46.0% of the time.

The five most likely winners for each scenario (no Rose, current ratings, full strength Rose) are listed below.  The Bulls with a full strength Rose are clearly the best of the bunch.

In the end, Derrick Rose’s ACL injury is very bad for the Bulls, and leaves a lasting impact on the playoffs.

Because Rose’s health issues this season were already somewhat factored into our playoff projections, the Bulls’ drop from Current Ratings (30.6%) to No Rose (11.8%) underestimates the impact of Rose’s absence.

The Bulls don’t merely go from contender to pretender. In reality, they go from juggernaut to dark horse — but a dark horse that still has a chance.