RPM and the Good Back-Up Phenomenon

[Jinxed]

Could having a good back-up impact your RPM (or APM, or RAPM) in a negative way?

I first noticed this phenomenon back when Dwight Howard got a fairly low APM score over at basketball value for the 2009 season in which the Magic made the finals. That year his back up Gortat really came to prominence and played well, posting a ws/48 of .202 although his APM numbers were bad. Both Gortat's and Howard's APM were lower than what would be expected given their perceived value, and what other stats were saying.

http://basketballvalue.com/teamplayers. ... 9&team=ORL

I figured what was happening was that with little differentiation between play at the center position when Howard sat on down (or less than would be expected when a superstar goes to the bench) that the regression was then awarding the impact to other players on the court, particularly fairly higher scores than would be expected of Rashard Lewis and Jameer Nelson.

This year I have noticed a similar effect with the Gasol brothers. Both Marc and Pau have lower RPM's than would be expected ..

Marc, 2 years removed from defensive player of the year has a DRPM of 1.75, which ranks 22nd amongst centers. Perhaps Gasol's defense has slipped as he has put more energy into offense, but am I really to believe that he is having only the same defensive impact as Stephen Curry? Or is something funky going on considering that Marc's backup Kosta Koufus is a defensive stalwart himself?

As for his brother Pau, an all-star starter this year, but his RPM only ranks him 38th amongst Power Forwards! His back up Taj Gibson's RPM is also way down despite putting up nearly identical PER and WS to last season. They also have a 3rd good PF on the team in Mirotic..

Does having a good back up negatively effect your RPM?

Thoughts?

[Crow]

This issue has been raised a number of times over the years. It is a real concern but difficult to resolve. Strategies for trying to look beyond it include the 14 year RAPM metric and looksking at same 4 raw plus minus.