The All-Star break gives us a few days off from the daily drumbeat of baseball, an opportunity to take stock of what’s happened so far and assess how the rest of the season is likely to play out. Can the surprising Brewers continue their improbable run, or will the disappointing Cubs finally come to life? Will the Astros and Dodgers give us the first pair of 100-win teams since 2004, and can they play deep into October? Will Mike Trout resume his MVP trajectory? Will Aaron Judge and Cody Bellinger lead their leagues in home runs as rookies? Will MLB come clean about the ball being juiced?
I have no idea. But I have compiled of list of things that are at least likely to occur.
Here’s what I did. Using the Baseball-Reference Play Index Split Finder, I looked at the first- and second-half splits for every team in every season since the 30-team era began in 1998. That gave me 19 seasons of data for the majors as a whole, and 570 team seasons. Then I looked for disparities between the first and second halves of the season (with "half" defined as before and after the All-Star break). For example, in 10 of the 19 seasons (53 percent), the batting average was higher in the second half of the season than in the first, and this was true for 293 of the 570 teams (51 percent). I looked for metrics that were noticeably different between the two halves.
(One technical note: I looked at the number of seasons and number of teams, rather than the actual averages, for two reasons. First, the split between the first and second “halves” is not consistent. The number of games in the first “half” ranged from 83 (2012 Nationals) to 97 (2014 Dodgers and Rays). Second, I didn’t want my overall averages thrown off by years in which there was a very large difference between the halves, e.g. the home run spike in the second half of 2015, which was absolutely positively not caused by anything involving the ball, no really.)
More relievers pitching fewer innings
This one is pretty much money good. In every season since 1998 other than 2000, there have been more relievers per game in the second half of the season than in the first, and relievers have, on average, pitched fewer innings per appearance in every season. Of the 570 teams, 67 percent have used more relievers per game in the second half, and 66 percent have had their relievers pitch fewer innings per appearance.
These figures, of course, are greatly polluted by September call-ups, which allow managers to bring in an endless stream of relief pitchers in every game. Through July 8, there have been 3.10 relievers per team per game, the third-highest usage of all time, so last year’s record of 3.15 looks vulnerable. The year-to-date average of 1.08 innings per reliever is only the 12th-lowest of all time so far, so while it will go lower in the second half, 2015’s record of 1.01 could be safe.
Fewer innings by starters
In 14 of the 19 seasons (74 percent), starting pitchers threw fewer innings per start in the second half than in the first, and this was true of 315 teams (55 percent). This, too, is related to September call-ups, which allow managers to take the ball from starters earlier and hand it to the aforementioned endless stream of relievers. Last year, starters averaged 5.65 innings per start, the first time the average starter failed to complete 5 2/3 innings. The average to date this season is 5.59. We’ll set another record.
More home runs
Yeah, another record. In 13 of 19 seasons (68 percent), the home run pace—measured by at-bats per home run—was higher in the second half of the season than the first. This was also true of 302 teams (53 percent). Blame it on the weather, blame it on expanded rosters (and diluted pitching), blame it on batters finding their groove after struggling to get their timing down at the start of the year. Whatever, it seems pretty likely, if not a lock, that this year’s record home run pace of 1.26 per team per game through Saturday night’s games will rise, rather than fall, by season’s end.
Teams have struck out 8.24 times per game so far this season, on pace to shatter a record that’s been broken in each of the past 10 seasons. In 12 of 19 seasons (63 percent), the rate of strikeouts per plate appearance has been higher in the second half of the year than the first, and 347 teams (61 percent) have experienced a rise. So, yes, strikeouts seem certain to join relievers per game, fewest innings per starter, home runs per game, and possibly fewest innings per reliever as entries in the record book that list "2017" at the top of the all-time list.
For whatever it’s worth, though, don’t expect a Three True Outcomes hat trick. In 11 of 19 seasons (58 percent), there have been fewer walks per plate appearance in the second half of the year than the first, and 330 teams (also 58 percent) have experienced a decline.
More hit batters and intentional walks
These aren’t particularly common events, and the supporting data isn't as strong as for the measures I’ve already listed. But in 13 of 19 seasons (68 percent), there have been more hit batters and intentional walks (measured as a percentage of plate appearances, from the point of view of batters rather than pitchers) after the All-Star break than before. However, these trends aren’t supported on the team level, as just 286 teams (50.2 percent) experienced a rise in hit batters and only 282 teams (49.5 percent) were intentionally walked more frequently.
I listed these two, though, because both are in near-record territory. As I noted last week, batters this year are being hit at the ninth-highest rate since 1901. That seems likely to hold, or perhaps even climb, though it may not affect your favorite team’s hitters. As for intentional walks, the new don’t-bother-pitching rule notwithstanding, they currently represent 0.52 percent of all plate appearances, the third-lowest rate ever, slightly behind 2015 and 2016. (You are forgiven if you haven’t been paying attention to this record chase.) If the pattern of two-thirds of the past 19 seasons holds, the 2016 record will stand.
For many other figures, including runs per game, OPS, and base stealing, the data of the last 19 years doesn’t suggest that we’ll see much of a change in the second half of the year. But it appears that we can all look forward to more pitchers pitching fewer innings, more home runs and strikeouts, more hit batters and, perhaps if we’re lucky, more managers wiggling four fingers at the home plate umpire.
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