3ball
01-26-2019, 09:57 AM
"There are limitations on all box score stats – if the box score doesn't measure a particular contribution, a box-score-based metric can only approximate that contribution. This is not a great hindrance on the offensive side, as nearly everything of importance on offense is captured by the box score (only missing things like screen-setting), but on defense the box score is quite limited. Blocks, steals, and rebounds, along with minutes and what little information offensive numbers yield about defensive performance are all that is available. Such critical components of defense as positioning, communication, and the other factors that make Kevin Garnett and Tim Duncan elite on defense can't be captured, unfortunately.
What does this mean? Box Plus/Minus is good at measuring offense and solid overall, but the defensive numbers in particular should not be considered definitive. Look at the defensive values as a guide, but don't hesitate to discount them when a player is well known as a good or bad defender."
https://www.basketball-reference.com/about/bpm.html
The bolded red shows the fallacy of defensive BPM - it primarily measures defensive boards, steals and blocks (and steals are much more valuable than blocks in the formula)..
So bird has higher DBPM than pippen because of higher defensive rebounds and comparable steals.. any frontcourt player that gets steals will have high BPM because they already have high defensive boards..
similarly, today's PG's have an edge because they have high defensive rebounds coupled with their naturally higher steals levels - that's why Westbrook's higher DBPM in recent years destroy pippen's highs, despite being an inferior defender... Guys like harden get higher BPM than Bruce Bowen many years because Bowen wasn't a steals or defensive rebounds guy
So look at Bird's DBPM - it's 2.5.. so that means his defense adds 2.5 points to the scoreboard every 100 possessions, or more than Pippen's... but we know this is bullshit because DBPM is just a rebound and steals tracker... Ditto on Westbrook's DBPM - it's just a rebound and steals tracker... Ditto harden over Bowen... And ditto Pippen's - we know he's a great defender, but not based on his DBPM, which is just a counter of a couple select stats.
TLDR: the creators of BPM say defensive BPM is bullshit because it tracks only a few defensive metrics, while offensive BPM is good because it captures most of the offensive metrics
.
What does this mean? Box Plus/Minus is good at measuring offense and solid overall, but the defensive numbers in particular should not be considered definitive. Look at the defensive values as a guide, but don't hesitate to discount them when a player is well known as a good or bad defender."
https://www.basketball-reference.com/about/bpm.html
The bolded red shows the fallacy of defensive BPM - it primarily measures defensive boards, steals and blocks (and steals are much more valuable than blocks in the formula)..
So bird has higher DBPM than pippen because of higher defensive rebounds and comparable steals.. any frontcourt player that gets steals will have high BPM because they already have high defensive boards..
similarly, today's PG's have an edge because they have high defensive rebounds coupled with their naturally higher steals levels - that's why Westbrook's higher DBPM in recent years destroy pippen's highs, despite being an inferior defender... Guys like harden get higher BPM than Bruce Bowen many years because Bowen wasn't a steals or defensive rebounds guy
So look at Bird's DBPM - it's 2.5.. so that means his defense adds 2.5 points to the scoreboard every 100 possessions, or more than Pippen's... but we know this is bullshit because DBPM is just a rebound and steals tracker... Ditto on Westbrook's DBPM - it's just a rebound and steals tracker... Ditto harden over Bowen... And ditto Pippen's - we know he's a great defender, but not based on his DBPM, which is just a counter of a couple select stats.
TLDR: the creators of BPM say defensive BPM is bullshit because it tracks only a few defensive metrics, while offensive BPM is good because it captures most of the offensive metrics
.