Factor 1: It takes more pitches to complete a no-hitter than ever before.
This season, batters are making pitchers throw a record 3.93 pitches per
plate appearance, up from 3.89 last year, 3.83 in 2015 and 3.74 in the early
2000s. Outs take more pitches than hits, and strikeouts take more pitches
than other outs, and strikeouts are a bigger percentage of outs than they've
ever been. For that matter, walks (which take the most pitches of all) are
much more common than they've been in any season since 2000.
原因一:这个原因会比以前投出无安打比赛花更多用球数。这一季打者每个打席所花的
球数是3.93颗，比去年的3.89颗，2015年的3.83颗以及2000初期的3.74颗还要多。
出局所花的球数比击出安打还要多，而投出三振比任何出局方式用球数都还要多
而三振占了比赛的大部分的出局数。而且，从2000开始四坏球变得更普遍。
If we look at all the games in which a team threw nine innings and allowed no
hits or one hit, the number of pitches required to get the 27 outs has been
steadily rising. In the 1990s, the median pitch count in these games was 114.
In the 2000s, it was 115, in the first half of this decade it was 117, and in
2016-2017 it was 120. This year, the median is 125 pitches. Most of those are
one-hitters, so knock off three or four pitches from those averages to
reflect one fewer batter, but the rise is real.
如果我们整季关注一支球队在九局比赛内没有安打或是一支安打，则用球数则会要抓27
个出局数而逐渐上升。在90年代，整场比赛的用球数的中位数是114颗。在00年代则是
115颗，在2005年时来到了117颗，到了16-17赛季是120颗。今年的用球数中位数是125颗
大部份这些是一安打比赛，所以可从平均值少算三或四球反映多出来的一个打者但有
上升是真的。
Factor 2: The occurrences of 120-pitch starts have gotten really rare. We all
know that teams are more sensitive about pitch counts, and that on average
pitchers get pulled from games earlier than ever. But it's not just on
average: On the extremes, in the very best starts, teams are far less likely
to let a pitcher go deep. Last season, 95 percent of starters were pulled at
110 pitches or fewer. Just seven years ago, the 95th percentile pitch count
was 117, and in 2000 it was 124