LeeLou李儒 算計之帷

原文網址:
http://hangtime.blogs.nba.com/2014/02/26/sportvu-uncontested-jumpers-vs-okc/

In our Q and A at All-Star weekend, Oklahoma City Thunder coach Scott Brooks said that when his team is on defense, he’s “concerned about making sure that every shot is contested.”
Contesting every shot is impossible, but Brooks’ team certainly can do a better job. According to SportVU, no team has contested a lower percentage of its opponents’ jump shots than the Thunder . They’ve contested just 24 percent of opponent jumpers, a mark well below the league average of 31 percent.

奧克拉荷馬雷霆的總教練Scott Brooks在全明星週末接受訪問時表示，他對防守最重視的是讓每個投籃都被干擾到。
基本上這是不可能的，但Brooks無疑還有要求的空間。根據SportVU的統計，針對跳投的防守，找不到比雷霆更差的球隊了。他們僅僅跟上了對手24%的跳投，遠低於聯盟的平均值31%。

SportVU defines a jump shot as any shot out outside of 10 feet. It’s contested if a defender is within four feet of the shooter.
There’s a much stronger correlation between defensive efficiency and opponent effective field-goal percentage (EFG%) than between defensive efficiency and any of the other “four factors” (rebounding, forcing turnovers, keeping opponents off the free-throw line).

事先說明一下，SportVU定義10呎外的出手為跳投，而投籃者的4呎內有守方球員便算是防守到位(contested)。
在防守四要素裡，對手的有效命中率(eFG%)和防守效率(DefRtg%)有最強的相關性。(其他三項為對手的進攻籃板率OREB%，失誤率TO Ratio和罰球投籃比FTA Rate。)

Here’s the thing, though. The Thunder rank fourth in opponent EFG% and fourth in defensive efficiency. They’ve been a great defensive team — even though they haven’t contested jump shots very well. There is a correlation between the percentage of jumpers a team contests and its opponents’ EFG% (and in turn, their defensive efficiency). The Thunder are an outlier.

不過重點來了，雷霆對手的有效命中率和他們的防守效率都在聯盟裡排名第4，即使對跳投的壓迫不到位，一直以來他們都是支很棒的防守強隊。然而防守跳投到位的百分比和對手的eFG%其實是有關聯的(亦即是和防守效率有關)，所以雷霆的狀況是個特例。

They have defended the rim well. They rank fifth in opponent field-goal percentage in the restricted area, with Serge Ibaka ranking among the top individual rim protectors. That’s obviously important.
But, by itself, it doesn’t account for how high the Thunder rank in opponent EFG%. Not only do they not contest jumpers very well, but they don’t really force bad shots. About 61 percent of their opponents’ shots have come from the restricted area or 3-point range, the seventh highest rate in the league.

當然他們對籃框的保護很出色，將對手在禁區的投籃命中率壓制到NBA第5低，其中Serge Ibaka是聯盟中最頂尖的禁區守護神之一，這顯然是其中的關鍵。
但是這樣還不足以說明為何雷霆在對手的eFG%有如此優秀的表現。因為他們不只對跳投的防守不夠，也無法迫使對手選擇沒有效率的出手。與他們對陣的球隊，大約有61%的出手是在禁區或三分線外，這是全聯盟第7高的數字。

So how have they been so good defensively? They do rank in the top 10 in defensive rebounding percentage and are slightly above average at forcing turnovers. But you have to wonder if there’s a little luck involved. Take the following numbers into account…
- Thunder opponents have shot 38.7 percent on uncontested jumpers, the sixth lowest rate in the league.
- Thunder opponents have shot 30.5 percent on contested jumpers, the second lowest rate in the league.
- Thunder opponents have shot 72.2 percent from the free-throw line, the second lowest rate in the league. (What goes around comes around; they ranked 28th in free-throw defense last season.)
- Only one other defense (the Lakers) ranks in the top 10 in each of those three categories. Five other teams rank in the top 10 in two of the three.

那麼雷霆到底是如何守住對手的? 他們確實擁有前10名的防守籃板率DREB%，迫使對方產生失誤的能力也略高於聯盟平均，但你可能忍不住懷疑有沒有一點運氣的成份在裡頭。讓我們看看下面的數字…
- 雷霆對手的跳投沒有被守到時命中率是38.7%，聯盟第6低。
- 雷霆對手的跳投被守到時命中率是30.5%，聯盟第2低。
- 雷霆對手的罰球命中率是72.2%，也是聯盟第2低。(風水輪流轉，上一季他們對手的罰球命中率是第28低，也就是第3高。)
- 除了雷霆，只有湖人在上面三項數據都排進前10，另外也只有5支球隊能在其中兩項同時進到前10。

Now, the definition of what’s contested (see above) allows for some leeway. It could mean that the defender is six inches from the shooter with his hand in his face, and it could mean that he’s 48 inches away with his hands down. Maybe the Thunder contest to a different degree than other teams. But they don’t contest a lot.
Eliminating the possible “luck” factor, the Thunder are still a good defensive team. If OKC opponents had shot the league average on contested jumpers, uncontested jumpers and free throws, the Thunder would have allowed 86 more points this season (about 1.5 more per 100 possessions) and would rank seventh in defensive efficiency (in part because there’s a dropoff after the top seven).

現在看來，關於防守到位(contested)的定義或許有些產生誤差的空間。它可能意味著一名防守者在6吋的距離內緊逼出手球員，同時將手遮住他的臉。它也可能代表防守者剛好雙手下垂地站在距離48吋的地方。也許雷霆的防守壓迫程度不同於其他隊伍，但是卻無法常常跟到位。
因為即使排除運氣的成份，雷霆仍然是支優秀的防守球隊。如果上述三項雷霆對手的命中率都回到平均水準，他們本季將會多丟86分(DefReg%大概增加1.5分)，這將讓他們的防守效率排到第7(某種程度上是因為第7名以後有個巨大的落差)。

But they have had trouble slowing down Golden State, one of the league’s best jump-shooting teams, the team that has been the most efficient against the Thunder this season, and a possible first-round playoff opponent. In his three games against the Thunder, only 21 of Stephen Curry‘s 66 field goal attempts have been contested (just three of 22 on Nov. 14).
Some other good jump-shooting teams — Atlanta, Miami and Portland — also have had decent success against the Thunder. Others — Dallas and Phoenix — have not.

不過他們在面對超會跳投的金州勇士時遇到了大麻煩，這支本季對雷霆打得最有效率的球隊，很有可能是他們季後賽的首輪對手。在本季三次交手中，Stephen Curry總共66次的出手只有21次有人防守(11/14時更是只有3-22)。
其他擅長跳投的球隊中，老鷹、熱火和拓荒者也都對雷霆有不錯的進攻效率，而小牛和太陽則沒辦法。

In this first full season of player tracking, there are still some things to figure out. And maybe things will be different defensively for the Thunder with a healthy Russell Westbrook. But if Brooks’ goal is to contest every shot, his team has some work to do.

本季是啟用player tracking系統的第一個完整球季，看來還有一些問題待釐清。或許當Russell Westbrook健康歸來以後一切又會不一樣，然而如果Brooks的目標是干擾所有的出手，他們還需要更多的努力。