大部球迷不懂效率？美球迷以哈登納什為例，帶你理解真實投籃效率

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大部球迷不懂效率？美球迷以哈登納什為例，帶你理解真實投籃效率

[OC] Understanding true shooting efficiency: comparing James Harden and Steve Nash (self.nba)

理解真實的投籃效率：用哈登和納什進行對比。

A remarkable number of people on here don"t really understand efficiency in an NBA context and overrate shooting percentages. So here lets compare James Harden this season and Steve Nash in the 08-09 season.

Why this comparison?

Harden has a slightly higher true shooting this season than Nash did that season, despite having way worse 3% and FT%. That makes it a great way to examine how true shooting differs from raw percentages (and why its more useful).

(Also, this won"t address turnovers, which are an important element of efficiency but not one that any of these percentages can address.)

論壇里很大一部分人都沒有真正的理解NBA里的效率是何物，只是一味的高估投籃命中率。所以這裡我想拿這賽季的哈登與08-09賽季的納什進行一下比較，幫助大家真正理解效率。

為什麼選擇這樣一組對比？

儘管這賽季哈登的真實命中率要比當時的納什稍微高一點點，但是在三分命中率和罰球命中率上，哈登都遠遜於當年的納什。所以這樣的對比就能非常有力的說明真實命中率和命中率的差別究竟在哪（以及為什麼前者更有用）。

（另外，這個數據並沒有體現失誤，雖然失誤對於效率的影響很大，但是無論是命中率，還是真實命中率，都沒法體現失誤的影響）

What are the numbers?

具體數據如下

Does this discredit True Shooting?

Not at all. True shooting is actually a calculation of points per shooting attempt, masquerading as a percentage.

Efficient scoring breaks down into three key parts: shooting good percentages, taking more shots from places where you have great percentages, and avoiding turnovers. Traditional shooting percentages do the first, and do nothing to tell you about the second or third. True shooting does the first and the second.

這個數據對比會不會貶低真實命中率的作用？

完全不會。真實命中率實際上衡量的是你每一次出手能得到多少分，只是看上去像比率罷了。

有效率的得分可以分解為以下三個關鍵方面：高命中率的投籃，更多的在你投籃命中率高的地方出手，同時減少失誤。傳統的投籃命中率只能顯示第一個方面的表現好壞，而無法表達出後面兩個方面。而真實命中率則能同時包含前兩個方面。

The actual formula for true shooting:

True shooting% = Points/(2 * (FGA + .44 * FTA))

計算真實命中率的公式：

真實命中率%=得分/（2*（出手次數+0.44*罰球次數））

Broken down:

• 
  

  .44 * FTA:

Because box scores were invented decades ago when people didn"t know as much about the game, box scores are kind of shitty. They record free throws without keeping information about how the free throws were obtained, on "+1" attempts, when attempting a 2-point field goal, or when attempting a 3-point field goal. Because of that a box score doesn"t actually include per possession information for each player, it includes FGA but doesn"t include attempts that led to multiple free throws.

What does this actually mean? It means true shooting is trying to calculate shooting possessions from box score information that deliberately hides it. .44 * FTA is an attempt to calculate the actual number of possessions used, but it causes true shooting to underrate certain players (players like Lebron who get a ridiculous number of "and 1" attempts, and Harden who gets a ridiculous number of fouls on 3-point attempts).

具體分析：

0.44*罰球次數：

因為早在人們對籃球還不怎麼了解時，技術統計這種東西就已經被發明了，所以技術統計實際上是很簡陋的統計方式，它只記錄了罰球的次數，而對具體的方式隻字不提。它不會告訴你這個罰球究竟是怎樣的出手換來的，是兩分投籃出手，或是三分投籃出手。正因為如此，技術統計上的分數反應不了一個球員每一回合所能得到的分數，它記錄了球員的出手次數，但是卻不包含那些造成了罰球的出手。

那這究竟意味著什麼呢？意味著真實命中率努力想要從技術統計里通過計算得出球員的真實出手次數，而這正是技術統計故意不記錄的數據。0.44*罰球次數正是想要計算球員們的真實出手次數，但是這樣的演算法也讓某些球員的真實命中率受到了低估（比如勒布朗這種得到非常多「2+1」的球員，以及哈登這種非常多造3分犯規的球員）。

• 
  

  (FGA + .44 * FTA)

By adding FGA to the calculation of possessions used for free throws, TS gets an estimate of total possessions used on shooting attempts.

出手次數+0.44*罰球次數

通過出手次數加上罰球次數的特定比例這樣的演算法，真實命中率便得到了球員真實出手次數的一個估計值。

• 
  

  Points/(FGA + .44 * FTA)

Here true shooting calculates points per shooting possession. In the case of Harden, that is 1.236 this season, which means that when Harden attempts to take a shot, he averages 1.236 points.

得分/（出手次數+0.44*罰球次數）

這裡真實命中率衡量了每一回合的得分，以哈登為例，這賽季他的這一數據為1.236，也就是說，當哈登出手一次投籃時，他平均能得到1.236分。

• 
  

  Points per shooting possession / 2

Because people are familiar with shooting percentages, the points per shooting possession is divided by 2 to make it look like a percentage. Thus it becomes "true shooting percentage" even though it actually has nothing to do with a percentage.

每回合得分數/2

因為人們都熟悉了投籃命中率，所以這裡把每回合得分數除以了2，從而讓它看起來像個百分率。從而「真實命中率」這個稱呼也就由此而來，儘管它實際上和百分率沒啥關係。

So, now that we know TS% is not a percentage, but actually points per shot attempt, why does Harden do so well on it in the previous comparison, even though Nash crushes him in 3-point % and free-throw %?

Lets compare where Harden gets his points from and where Nash got his points from. To make the comparison easier to interpret, lets reduce Harden"s possessions to match that of Nash.

所以，現在我們知道了真實命中率其實並不是百分比率，而是每一次出手所能得到的真實分數。那麼為什麼哈登能在三分命中率和罰球命中率落後納什這麼多的情況下還在真實命中率這一項上做得這麼好呢？

下面讓我們比較一下哈登和納什分別都在球場的哪塊區域得分。為了讓這個比較簡明易懂，讓我們把哈登的回合數縮小到和納什一樣。

Nash points per shot attempt: 1.228

Nash true shooting: .614

納什每一次出手所得分：1.228

真實命中率：0.614

Harden points per shot attempt: 1.233

Harden true shooting: .617

哈登每一次出手所得分：1.233

真實命中率：0.617

Here we can see that despite his inferior percentages, Harden gets just as many points from his attempts, because he gets way more free throws, and he shoots way better on his free throws than Nash does on his 2-point attempts or 3-point attempts.

The lesson from this is that shooting percentages can be misleading. To understand a player"s efficiency, we need to know how many possessions they use at different types of shots. A player can be a worse shooter than somebody else, and make up the difference by getting taking more shots of the type they shoot the best.

這裡我們就能看出，為什麼哈登在投籃命中率處於劣勢的情況下每回合仍然能得到類似的分數，因為哈登創造了太多的罰球，而且他在罰球上的表現比納什在兩分和三分出手上的表現要好得多。

結論就是，投籃命中率有時候會引起誤解。為了了解一個球員的效率，我們需要知道他在不同類型的投籃上分別出手了多少次。就算一個球員的投射能力比其他所有人都差，他也可以通過更多的出手自己最擅長的投籃，從而彌補這一差別。

[–]i_miss_arrow[S] 16 指標 3 天前

As a quick followup to something I briefly mention:

Lebron and Harden are both underestimated by TS%. They both have a TS% around .617, but using their actual possessions rather than estimated from free throws gives a true shooting around .625.

A small effect but an interesting one, considering the ridiculousness of the MVP race this season.

作為一個快速的補充，我簡要的提一下下面這個事情：

哈登和勒布朗的真實命中率都被低估了，他們的真實命中率都在0.617附近，但是如果用他們在場上真實的回合次數，而不是通過加入罰球次數而獲得估計值的話，他們的真實命中率應該在0.625附近。

這是個小的影響，但是非常有意思，考慮到這賽季MVP競爭的激烈程度。

[–][SEA] Kevin Durantguga31bb 8 指標 3 天前

This will happen with any player who disproportionately gets free throws from 3 pointers, and 1s, or techs, since the TS% calculation "thinks" they used more possessions than they actually did. Harden, especially, draws a lot of fouls on 3 pointers.

對於那些獲得超出常規的三分造犯規，2+1，或者技術犯規的球員來說，這就很適用了。因為真實命中率「認為」他們使用了比實際更多的出手次數。尤其是哈登，他造了非常多的三分犯規。

[–]i_miss_arrow[S] 5 指標 3 天前

Yeah. Harden"s effect is as you said, and Lebron has a ton of "and 1" free throws along with a decent number of 3-point fouls.

是的，哈登情況正如你所說，而勒布朗則有大量的「2+1」進球，外加可觀的三分出手被犯規數。

[–]Hawkspln1991 6 指標 3 天前

That"s a long writeup of something I assumed was fairly well understood. But I"m probably wrong, and it"s probably not understood as well as I think/hope. So good job.

我認為這算是長帖子里比較容易理解的一帖了。但是也許我錯了，也許它並沒有我想的這麼容易被理解。總之，樓主做得很不錯。

[–][SAS] Tim Duncanrattatatouille 3 指標 3 天前

Simpson"s paradox at work here. Because TS% really likes players who shoot a lot of FTs it favors them even if their percentages are strictly worse.

Which makes sense - unlike FG% and FT% which delineate how well a player shoots from particular areas TS% shows how efficient they are scoring om a per possession basis.

辛普森悖論這裡就出現了。因為真實命中率非常偏好大量獲得罰球的球員，所以就算他們的命中率很爛，這項數據也會很好看。

這也就說得通了——不像投籃命中率和罰球命中率這種能夠確定描述出球員在特定區域投籃命中率的數據，真實命中率則是基於每一回合上顯示了球員的效率。

[–]76ersImaginaryCam 9 指標 3 天前

It"s gonna be a damn shame if Westbrook gets MVP for averaging 2 more rebounds than Harden despite the enormous gap in efficiency between them.

若威少因為場均比哈登多了2個籃板而拿MVP，那哈登就太可惜了，因為他倆的效率差太遠了。

[–]NBASolarClipz 5 指標 3 天前

Harden has an ENTIRE team built around him and his talents specifically.

Westbrook doesn"t.

哈登有著一整支為他量身打造的球隊。

而威少則沒有。

[–]Hawkspln1991 1 指標 3 天前

Also 2 more points

另外威少場均還多2分呢。

[–]76ersImaginaryCam 4 指標 3 天前

Let"s be honest, no one who thinks Westbrook is an MVP right now would change their mind if he averaged 2 less points. People are just obsessed with round numbers so they think there"s no way he can"t be the best if he"s averaging a triple-double.

平胸而論，那些現在認為威少是MVP的人根本不會因為少得2分就改變他們的觀點。人們只是對整數的數據太著迷了，以至於他們認為如果你場均三雙了，那你沒可能不是最強的球員。

[–][CLE] LeBron Jamesviniribeiro -2 指標 3 天前

I think TS% is a much worse stat that efg%, I dont get why the need to put FT% into it, Nash is quite clearly more effective than Harden imo

我覺得真實命中率是一個比有效命中率差得多的數據，我不理解為什麼要把罰球命中率放到裡面去，在我心中，納什顯然是比哈登更高效的球員。

[–]johncenatbh 10 指標 3 天前

Because getting to the line is super efficient, and a great skill to have a scorer.

因為能夠站上罰球線是非常高效的打法，也是一名得分手非常好的技術手段。

[–][LAL] Kobe BryantChampagnesoda 3 指標 3 天前

I fucking love Steve Nash but it"s not hard to argue harden is better now than Nash ever was

我超級喜歡納什，但是現在的哈登是比巔峰納什更出色的球員，這點沒什麼好辯的了。

[–][SEA] Kevin Durantguga31bb 2 指標 3 天前

If efficiency is points per possession (as it should be), then TS% is the right measure. Eliminating free throws makes no sense. They count as points and possessions too.

如果效率是指每回合的得分數（也應該是），那麼真實命中率就是正確的衡量方式。消除罰球的影響毫無道理，因為罰球一樣被算進了得分和回合數。

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