MarisFan61
KL: Now you're doing me too much credit!!
I take shortcuts all the time! But indeed that's not a kind that I would take -- unless I didn't see that it's based on 'impure' data, when purer data are right there too; unless I just didn't see what it was based on, which sometimes happens.
In short: There was every reason to wonder what I did.

You did a great job fleshing this out further.

It is unfortunate that Mark Simon and apparently others from his organization don't reply to comments here. But hopefully they take heed from them.

When they make mistakes like the one at the top up there, it seems they just don't know the history, and didn't think to take a quick look to confirm it, which wouldn't have been hard. Even taking shortcuts. :-)
11:37 AM Jun 1st

MarisFan61
Let me clarify, in case you might have thought otherwise, which it seems you might:

I didn't just use whatever ratios the site might show for flyballs vs. grounders, and I didn't use those sets of data that mish-moshed flyballs and line drives.

I did ratios on my own from the flyball and ground ball data, taken from the sets of data that do list fly balls separately from line drives.
The ratios that I used did reflect baseball-ref.com's "pure" flyball data.
10:20 AM May 31st

MarisFan61
(......but, terrific breakdown and analysis.
Just wondering what you meant about the merging-line-drives thing.)
11:23 PM May 30th

klamb819
Baseball Reference is a little misleading, because it merges line drives into fly balls. I prefer Fangraphs' flyball and groundball data for that reason, so I wandered over there. Going back to 2001:

---In 2006, the fly ball percentage spiked from 34.9% the previous year, up to 36.7%. (The decrease in line drives was much greater than the decrease in grounders.) The FB% stayed in that vicinity through 2011, peaking at 37.8% in 2009 (with the LD% down from its 22.5 peak in 2003 to 18.2 in 2010).

So: as drug testing began, fly balls rose by 3% and line drives went down by a bit more than 4%, circa 2003-2011.

--In 2012, the FB percentage plunged from 36.0 to 34.0. That rate stayed pretty steady through 2015, when it bottomed out at 33.8%. In that same four-year period, ground balls went up by 0.9%, making 2015 the century's highest year for GB/FB ratio: 1.34. The line drive rate had started going up a year earlier, in 2011, and rose by 2.7% in five years, to 20.9%, the highest since 2003.

Recapping so far: After rising and then falling, the FB% had a net decrease of 1.1% from 2005 to 2015, LDs fell and rose to a net change of 0.0% in 10 years. And ground balls decreased, then increased, with a 10-year change of +1.1%.

--Fly balls have gone up each year since 2015, never by as much as a full percent, but with a three-year gain of 1.8 percent to 35.6% so far this year, still well under the spike of 2006-11. And the increase is a tick under the ONE-year increase of 1.9% in 2009 (to its recent peak).
--The LD%, steady since 2012, has risen by only 0.3% since 2015.
--And ground balls, down 2.1% in a steady fall since 2015, have reached their lowest level since before 2002, which apparently is FG's first year of this data.

Also: wasn't 2015 also the first year of StatCast?

Maris is right about the more important, broader picture, too. We're not in a fly ball revolution. We're in a LAUNCH ANGLE REVOLUTION, and the angle being aspired to is kind of in between a line drive and a fly ball. This revolution has been driven by two things: Statcast's confirmation of the optimum revolution (which has given a revival to the Ted Williams axiom of meeting the pitch's downward plane with an uppercut swing).

And the routine infield shifting, which makes ground-ball hits increasingly harder to come by. That's the thinking, anyway. The data says the MLB batting average on ground balls has either increased or stayed the same every year since 2003, rising from that year's low of ,215 to last year's .241 (while the number of ground balls has fallen by more than 3,00). Go figure. (There were also two ground ball home runs in 2012.)

This article is fine for a general readership, but for BJOL subscribers, it is likely to draw the observation that "pulling fly balls" is actually two different things. Fly balls tend to go toward the opposite field more than the pull field, so pulling them is another matter entirely, and is probably as old as the live ball. However, the philosophy comes and goes, and two players' successes revived interest in pulling the ball to increase HR power. They did it several years before the fixation on launch angle. Jose Bautista began hitting home runs at a much higher rate toward the end of the 2009 season, and continued until he had hit 54 in 2010, which was more than his combined total for 2004-08. The next year, 2011, Curtis Granderson began consecutive seasons of 41 and 43 home runs, after hitting just 24 in 2010 and peaking at 30 in 2009.

The pull rate is up 1.5 percent since 2015, to 40.6%, but remains at least 2% below the pre-2006 plateau, which ended one year after routine PED testing, if I'm remembering the date correctly. Pulling the ball has not captured as much interest as optimum launch angle. But the article is right that combining the two is a prescription for home runs.



10:10 PM May 30th

MarisFan61
Side question:
Assuming there really are more fly balls now (is that for sure??), would that mean that fielding for outfielders has become relatively more important than before?

Seems it would have to.
At least relatively, compared to fielding for infielders; it wouldn't necessarily mean an absolute increase in importance, because of the general decrease of balls in play.
10:59 PM May 25th