※ [本文转录自 NY-Yankees 看板]
作者: leddy (耿秋) 看板: NY-Yankees
标题: Re: [统计] What is Zone Rating?
时间: Sun May 13 16:26:18 2007
※ 引述《leddy (耿秋)》之铭言：
: 因之前查Bobby Abreu的资料, 顺道查到这篇好文Hardball Times的好文
: 来源http://www.hardballtimes.com/main/article/what-is-zone-rating/
: What is Zone Rating?
什么是防守区域评价
: by Sean Smith
: April 02, 2007
: Zone rating has been around for 20 years now as a way to measure defensive
: players. It’s a simple concept; you just need to know two things: How many
: plays a fielder makes, and how many were hit into his zone. You divide the
: first number by the second, and you have zone rating. You can look at how
: many plays were made compared to an average fielder to get a plus minus
: rating, and that can easily be converted to runs to help us measure the
: overall worth of a ballplayer.
防守区域评价至今已经被用了大约二十年，是一种对防守球员评价的方法。这是一个
简单的概念；你只需要知道两件事；野手完成多少出局数；有多少球打进他的防守区域。
将第一个数除以第二个数，你就可得到防守区域评价的值。你可以看看这个野手完成多少
出局数与野手平均的出局数作比较，便可得到加或减的评价，这也可以很容易地转换为得
分数，用来帮助我们对一个防守球员作整体评价。
: There’s More than one Zone Rating?
: Last winter John Dewan and Baseball Info Solutions published The Fielding
: Bible and introduced a new version of zone rating. Dewan happens to be the
: guy who came up with the old Zone Rating when he worked for STATS, and he was
: able to add an improvement in the treatment of plays fielded outside of the
: zone.
不只有一个防守区域评价值
去年冬天John Dewan和Baseball Info Solutions于野手圣经上发表的文章介绍新版
的防守区域评价的方法。Dewan恰好是为STATS工作时想出旧版防守区域评价值的人，所以
他运用了野手在防守区域外拿到的出局数，以改进旧版防守区域评价的不足。
: In the original Zone Rating, if a ball is hit outside of your zone but you
: range far enough to make a play anyway, that ball is added to both your plays
: made and your chances. The effect of this is to underrate players with
: outstanding range. Here’s an illustration:
: Take two shortstops, call them Billy and Jason. Both players have three
: ground balls hit near them, two in the shortstop zone and one just beyond it,
: hit straight up the middle. Jason makes plays on the two hit in his zone but
: cannot reach the other ball. Billy makes one play in his zone, makes an error
: on the other, but makes a great play on the ball hit up the middle.
: The zone rating for Jason is a perfect 2/2. For Billy, its 2/3, even though
: both players have had the same opportunities, and recorded the same number of
: outs. The new Zone rating treats these plays differently. Balls in zone
: counts only those hit into your zone, and there is a separate category for
: balls fielded outside your zone.
在原始的防守评价值中，假如球被打出你的防守区域，但是你的防守范围够大还是拿
到出局数(接到了球)，此球被同时加到你拿到的出局数和防守的机会中。这样的结果低估
了一个有杰出防守范围选手的价值。举例来:
如果有两个游击手，就称呼他们比利和杰森好了。这两个防守球员有三个滚地球打到
接近他们的位置，两个在游击手防守的区域内，一个在防守的区域外直接打向中间而去。
杰森对打向防守区域内的两球拿到了出局数，但防守区域外的球根本构不到球。比利则对
打向防守区域内球拿到一个出局数，另一个则发生失误，但是打向中间跑出防守区域的球
却用美技式的让打者出局。以原始的防守区域评价而言，杰森是完美的2/2，但比利却是
2/3，即使两个防守球员有相同的防守机会，同时记录相同数字的出局数。新的防守区域
评价则将这些出局数视为不同。防守区域内的球(Ball in zone)只计算打进你防守区域内
的球，而将用一个类别的值记录落在你防守区域外的球。
: Let’s Check the 2006 Results:
: The new Zone Rating is now available on The Hardball Times website. THT has
: data for the 2004 to 2006 seasons, and will add 2007 data as soon as the
: games begin. To get a feel for how the new feature, balls out of zone,
: affects a player’s rating, let’s take a look at the shortstops for 2006,
: using the new data but calculated the same way as the old Zone Rating:
让我们看看2006的记录：
新的防守区域评价现在可以在The Hardball Times(THT) 的网站中查得到。THT有2004
至2006年球季的资料，而且将在球赛开始进行后尽快加入2007年的资料。来感觉一下新的
数字，防守区域外接捕的球(balls out of zone)，对一个防守球员评价值的影响。就看看
2006年游击手的的数字，我们先用新的资料但用旧的防守区域评价的方法去计算：
: Name BIZ Plays ZR OOZ Chance Total Plays Above
: Plays AVG
: A. Everett 396 353 0.891 60 456 413 28
: O. Vizquel 352 306 0.869 36 388 342 14
: J. Reyes 359 308 0.858 40 399 348 11
: C. Barmes 315 269 0.854 51 366 320 11
: J. Bartlett 293 253 0.863 26 319 279 10
: A. Gonzalez 269 230 0.855 42 311 272 9
: E. Renteria 368 309 0.840 55 423 364 7
: D. Eckstein 320 269 0.841 43 363 312 5
: J. Uribe 333 280 0.841 40 373 320 5
: K. Greene 286 238 0.832 36 322 274 2
: R. Cedeno 322 265 0.823 54 376 319 1
: J. Rollins 413 342 0.828 46 459 388 0
: J. Wilson 401 330 0.823 48 449 378 -1
: M. Young 458 375 0.819 53 511 428 -3
: B. Hall 294 234 0.796 66 360 300 -4
: C. Guillen 406 330 0.813 49 455 379 -5
: R. Furcal 458 372 0.812 57 515 429 -6
: Y. Betancourt 399 322 0.807 55 454 377 -6
: M. Tejada 394 318 0.807 44 438 362 -8
: D. Jeter 385 310 0.805 28 413 338 -11
: H. Ramirez 368 290 0.788 61 429 351 -11
: A. Berroa 364 286 0.786 36 400 322 -16
: J. Peralta 459 364 0.793 46 505 410 -16
: O. Cabrera 351 273 0.778 44 395 317 -17
: Definitions:
: BIZ: Balls in zone
: Plays: Plays made in zone
: ZR: Zone rating
: OOZ: Plays made out of zone
: Chances: BIZ + OOZ
: Total Plays: Plays + OOZ
定义：
BIZ: 防守区域内的球
Plays:防守区域内拿到的出局数
ZR: 防守区域评价
OOZ: 防守区域外拿到的出局数
: Plays above average is found by finding the league average ZR, multiplying by
: Chances, and comparing to total plays made. This is for illustration
: purposes; I am using the total of this group of qualified players instead of
: the actual league average which would include starters and reserves. In
: addition, Chris Dial uses (correctly in my opinion) the AL and NL averages
: instead of an overall MLB average. There are factors (such as pitcher
: hitting) that make within league comparisons more accurate than overall
: comparisons.
超出平均的出局数(plays above average)的计算方法是先找到全联盟的平均防守区域
评价(ZR)，乘以防守机会(Chances)，再防守员拿到全部的出局数比较。为了举例的目的，
这里所用的是列出的这群防守机会次数达到标准的防守球员的资料计算其平均数，而不是
用真正全联盟的平均数。而且以作者的意见而言，更正确的数值应该就像Chris Dial用的,
应分为美国联盟和国家联盟分别的平均数值，而非全联盟的平均值，因为一些因素(诸如投
手打击)的影响应该分别计算更为准确。
: Now, let's try this again, treating balls outside of zone separately, so that
: we correctly reward both reliable fielders in their zone and players who make
: more plays outside of their zone. I will find the league average using only
: BIZ and Plays, and then do a separate calculation for balls outside of zone:
现在，我们再重新计算一次，将防守区域外的出局数(balls outside of zone)分开计
算，如此我们可以对野手在他的防守区域内的判断能力(可靠度)，及防守区域外的防守范
围，都可以给予正确的奖励。
: Plays
: Above
: Name AVG Reliability Range New Total
: A. Everett 28 26 10 36
: O. Vizquel 14 16 -9 7
: J. Reyes 11 12 -6 6
: C. Barmes 11 9 11 20
: J. Bartlett 10 11 -11 0
: A. Gonzalez 9 8 8 16
: E. Renteria 7 6 8 14
: D. Eckstein 5 5 2 7
: J. Uribe 5 5 -2 3
: K. Greene 2 2 0 2
: R. Cedeno 1 -1 13 12
: J. Rollins 0 1 -7 -5
: J. Wilson -1 -1 -3 -4
: M. Young -3 -3 -5 -8
: B. Hall -4 -8 29 20
: C. Guillen -5 -5 -3 -7
: R. Furcal -6 -6 -1 -7
: Y. Betancourt -6 -7 4 -3
: M. Tejada -8 -7 -6 -13
: D. Jeter -11 -7 -21 -29
: H. Ramirez -11 -13 14 1
: A. Berroa -16 -14 -10 -25
: J. Peralta -16 -14 -12 -27
: O. Cabrera -17 -16 -1 -17
: We can compare the player’s OOZ plays to the average OOZ plays based on how
: many balls were hit in their zone. This is similar to what David Gassko and
: Chris Constancio did for defensive ratings in the Hardball Times Season
: Preview. For this to work we have to assume that the number of out-of-zone
: opportunities for players are proportional to their in zone opportunities.
: This may or may not be a good assumption. An alternative would be to use
: total ground balls as the denominator. A better way would be to create a
: measure of out of zone opportunities. For a shortstop we could take every
: groundball hit to the left of the third baseman or to the right of the second
: baseman, and subtract the ones already counted in the SS zone. This measure
: is not available, so for now I think using BIZ as an estimate is acceptable.
: “Reliability” is a measure using only balls in zone. For this group of
: shortstops, the average Zone Rating was .825. This group also made .1274
: plays out of zone for every ball hit into the zone. “Range” compares the
: player’s out of zone plays made to this average, and the new total is simply
: Range + Reliability.
我们可以比较防守球员在防守区域外(OOZ)的出局数和平均的防守区域外的出局数(用
打入他防守区域内的球为比例算出平均出局数)。这结果就像David Gassko和Chris
Constancio在Hardball Times Season上所作的防守评价。为了算出结果我们必须假定防守
区域外的防守机会是和防守区域内的防守区域是成比例关系的。这可能是或可能不是一个
好的假设。另外一种方法则是用全部的滚地球为分母。更好的方法则是记录防守区域外的
防守机会。对一个游击手而言，我们可以计算球打到三垒手的左边或打到二垒手的右边的
滚地球，再减掉已经计算打到游击区的滚地球，就得到防守区域外的防守机会。但此一值
目前尚无法取得，所以目前用防守区域内(BIZ)的防守机会为比例去估计应该是可以接受。
"可靠度"(Reliability)是评估打到防守区域内的防守能力。"范围"(Range)则比较防守员
在防守员在防守区域外取得出局数与平值值的差异，新的总合值(new total)则只是将
"可靠度"和"范围"相加。
: The Highlights:
: Jason Bartlett did very well in Zone Rating but made very few plays outside
: his zone. In the end, he’s just an average shortstop.
: Bill Hall at the first step look a little below average, but made a
: tremendous number of plays outside his zone. This year he is being moved from
: shortstop to center field, but this may be a mistake as he makes many more
: plays than the average shortstop.
: Derek Jeter looks a little below average at first, but he’s even worse than
: that. Jeter has very limited range. Only Bartlett made fewer plays outside
: the zone, but Jeter played almost 50% more innings than Bartlett.
: Hanley Ramirez looks below average at first, tied with Jeter, but made a
: great number of plays out of his zone. He’s actually average or slightly
: above.
: Adam Everett already ranked far above any other shortstop in the game, but in
: addition to fielding everything hit near him he has excellent range as well.
: He may be the best defensive shortstop since Ozzie Smith.
重点的游击手:
Jason Bartlett在防守区域评价的值相当漂亮，但在防守区域外拿到很少的出局数。最后
他只是一个平均水准的游击手。
Bill Hall一开始看起来是个有点低于平均值的游击手，但却在防守区域外拿到相当多数目
的出局数。今年他正由游击手的位置被移到中外野手，但这可能是个错误的决定，因为他
实际上比平均水准的游击手拿到超出相当多的出局数。
Derek Jeter最初看是个稍微低于平均水准的游击手，但是实际上是更糟。Jeter的防守范
围相当有限。只有Bartlett比他在防守区域外拿到更少的出局数，但是Jeter防守的局数
比Bartlett多出50%(换言之Bartlett是小样本，Jeter的值更准确)。
Hanley Ramirez最初看来也低于平均值，和Jeter差不多，但是他在防守区域外拿到很多的
出局数。他实际上是平均水准或有一些高出平均水准的游击手。
Adam Everett已经排名高于所有的游击手，但注意的是他不仅防守区域内相当可靠，防守
范围也相当的大。他可以说是自Ozzie Smith之后最好的游击手。