Does D-League usage translate into more wins for NBA teams?

May 6, 2015; Houston, TX, USA; Houston Rockets center Clint Capela (15) in game two of the second round of the NBA Playoffs against the Los Angeles Clippers at Toyota Center. Mandatory Credit: Troy Taormina-USA TODAY Sports
May 6, 2015; Houston, TX, USA; Houston Rockets center Clint Capela (15) in game two of the second round of the NBA Playoffs against the Los Angeles Clippers at Toyota Center. Mandatory Credit: Troy Taormina-USA TODAY Sports /
Mandatory Credit: Troy Taormina-USA TODAY Sports
Mandatory Credit: Troy Taormina-USA TODAY Sports /

Winning in the NBA is what it’s all about, right? Owners are not looking to add D-League affiliates for the shear pleasure of seeing a player live out their childhood dream. At the end of the day, they are looking for quality players and coaches to help their team win games on, ideally, a cheap contract.

With that in mind, I collected data on D-League assignments and call-ups since the beginning of the 2009-10 season to see who has been active on both fronts (calling players up and winning) and ultimately to decipher whether or not their usage has been beneficial to this point.

It is important to first distinguish the difference between a call-up and an assignee. A call-up is a player who is signed from the D-League to the NBA. For example, if a player is on a D-League contract and is not attached to a specific team — the opposite of Kyle Anderson, who spent much of his rookie season in Austin — they are a call-up once they ink a deal in the NBA.

If a player on an NBA team’s 15-man roster is sent to the D-League to get some playing time, they are an assignee. This player can be assigned and recalled an unlimited number of times and they still take up an NBA roster spot while on assignment.

Call-ups since 2009

I chose to use 2009 for the data because the D-League started to flourish around that time — teams began using it like a standard minor league system. The system is by no means perfect at this point, but the pendulum is swinging in the right direction.

D-League Call-Ups since the 2009/10 season by team
D-League Call-Ups since the 2009-10 season, by team /

This graph has nothing to do with wins, but it does show the raw data of call-ups over the past six seasons. Some interesting tidbits:

  • Eight of the top 10 teams for call-ups have their own D-League affiliate
  • The Pacers haven’t had a single call-up (Note: They have NEVER had a call-up!)
  • You can find successful teams (by win percent) on both ends of this graph
  • There have been 275 total call-ups and the league average is 1.5 per season

Ultimately, this data showed that there is no correlation between call-ups and win percentage. Between the 13 teams with double digit call-ups, there were seven who finished above .500 and six who finished below that mark. As if there was any doubt, simply calling a player up from the D-League does not enhance your chances of winning at the NBA level.

It sure would be nice if life was that easy.

Assignments since 2009

Although I used data from the last six seasons, assignments hit their spike in 2012-13. In the 2011-12 season, there were only 61 assignments league-wide. In the following season, that rose to a staggering 179! That number (179) has held strong over the past three seasons, too.

NBA assignments from the D-League from 2009-2015 by team
NBA assignments from the D-League from 2009-15, by team /

This is where the data gets interesting. The orange bars in this graph show teams with a single-affiliation and the blue bars show teams without a single affiliation over this time. The Nets are the exception, as they had an affiliation with the Springfield Armor (now the Grand Rapids Drive) from 2009-14. For five of the six seasons shown, they were also a single-affiliate.

Here are the tidbits I pulled from this data:

  • There have been 671 assignments and the league average is 3.7 per season
  • The Bulls come in with the least at only three assignments over the past six years
  • The Thunder had the most assignments with 71
  • The Hawks used the system a ton for a non-affiliate team
  • The Magic, with a single affiliate in hand, have only had four assignments

Assignees and success

You’ll notice two distinct clusters in the graph below: one that shows teams with less than 30 assignments, the other showing teams with more than 40 assignments. For the teams that rarely use the D-League, there is no real correlation between winning and losing. But in the second cluster, there is a real correlation between assignments and success.

Relationship between assignees and NBA win%
Relationship between assignees and NBA win percentage /

For this study, success was measured in terms of point differential. Defining success can be subjective, so comparing point differential for teams ended up being our choice to show a real change from these assignees. Furthermore, the data showed no correlation between affiliate vs non-affiliate teams in terms of success, proving that even non-affiliate teams can help their NBA clubs by using the D-League to develop their players.

Of course, the correlation between assignees and success, while present, is weak at this point due to the fact that not all teams have their own affiliate to work with. Some teams have not used the assignee system and have still been successful, and vice versa. However, teams that do have a flourishing relationship with their D-League affiliate are much more successful on average than teams who do not have a great relationship.

This proves why there is a distinct difference between using the D-League for call-ups and using the league for assignments. Assignments are being used to develop an NBA team’s 15-man roster and thus, is far more successful on average than teams who try to simply develop in house.

Some of the more recent names being developed in this manner are Kyle Anderson (Spurs), Clint Capela (Rockets), Mitch McGary (Thunder) and Jordan Clarkson (Lakers). Anderson recently took home NBA summer league MVP honors and looks to be a real contributor for the Spurs in 2015-16. Capela was the NBADL darling last season and impressed whenever he got minutes with Houston.

The picture perfect example of this is from two seasons ago, when Robert Covington spent his entire rookie season with the Rio Grande Valley Vipers. He improved so much that he signed a four-year deal with the Sixers after the Rockets cut him. Now, he’s a real asset, fresh off of averaging 13.5 points and 4.5 rebounds in 2014-15 for the rebuilding franchise.

The D-League is certainly moving towards being a true minor league system for each parent club. While there are some teams who are still adverse to using the system — ahem, Bulls and Pacers — the teams who are committed to this valuable resource are already reaping the benefits.

It’s time to jump on board and ride the new wave of development, people.

Shout out to @HalBrownNBA for his assistance with the graphics.