Baseball-Reference‘s Play Index shows games since 1930 with starting pitchers batting in most batting order positions but most commonly, of course, in the number 9 hole. Next most common, by far, is batting the pitcher eighth, a tactic which has become more popular in recent years, exceeding 10% of team games this season and last. That is a huge departure from past practice as, other than in the mid-1950s and in 1998, there were virtually no such games before 2007. The question then is why has batting your pitcher eighth now come somewhat into vogue?

You can weigh in on this question after the jump.

Here’s the chart, illustrating the trend in games with the pitcher batting somewhere other than 9th.

Those recent games include 36 since 2008 (none prior) with both starting pitchers batting eighth; 25 of those 36 have come in the past two seasons.

It’s probably better at this point to term batting pitchers eighth as an experiment more than a trend. That assessment is illustrated by the table below showing games by team for the past two seasons.

So, teams that experimented last year (Cubs, Reds, Mets, Padres) aren’t doing so nearly as much this year, while new teams (D-Backs, Braves, Phillies, Giants) are leading this year’s experiment.

Looking at players, these are the pitchers with the most starts since 2015 batting eighth.

Take those numbers with a grain (or more) of salt, but there are some batting averages in that list that would justify moving the pitcher up in the batting order (but many others that wouldn’t). Generally, though, teams that are using this strategy are doing so without discriminating among their different pitchers.

Some possible reasons for batting the pitcher eighth:

1. the pitcher is a better hitter than another starter
2. it helps to put a man on base for the top of the order (particularly attractive if a team can bat a second leadoff-type hitter in the 9 hole)
3. something more complicated

One thought under that third category is that teams might be batting their pitcher eighth to reduce the times that the pitcher will lead off an inning. Obviously every team wants to avoid that, but batting a weak hitter eighth ahead of the pitcher (the traditional approach) usually doesn’t help much in that regard when that weak hitter bats with two out. Swapping your 8 and 9 hitters might help to extend innings, assuming (usually correctly) that the no. 7 hitter is a somewhat better hitter than the man who follows him (in 2015, no.7 batters posted .697 OPS compared to .653 for no. 8 hitters). That no. 7 hitter hitter is likely to extend more innings:

• because he is a better hitter than the former no. 8 hitter
• being a better hitter, he is more likely to be walked ahead of the pitcher than the former no. 8 hitter
• even if he doesn’t extend the inning, by having the pitcher lead off the next inning with a weak hitter following, there’s a good chance of two outs when the top of the order comes up and, therefore, a reasonable chance that the inning will end before the meat of the order comes up (saving them to do some damage in the next inning)

I did a little investigation into this question using the 2015 data, but didn’t see any correlation between batting pitchers eighth and leading off innings less often. Possibly one reason for this result is that teams batting the pitcher eighth usually haven’t swapped the 8 and 9 hitters (maybe they should?), but instead have just moved their preferred leadoff-type hitter to the 9 hole (strategy #2 above) with the result that the pitcher still follows the next weakest hitter, who is now batting seventh.

To close, here are data for 2015 for players having 30+ PA batting eighth with two out ahead of the pitcher’s spot in the first through sixth innings (after the 6th inning the pitcher could be hitting almost anywhere in the order and will seldom bat in any case).

[table id=295 /]

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Notable that Nick Ahmed received no intentional walks in 83 PA in this situation (but that’s a subject for another post). Adeiny Hechavarria shines in this comparison, not only extending innings but doing some damage in the process with the sum of his RE24*LI scores more than twice that of any other player.