Tuesday, March 13, 2012

ACTIVE COMPARISONS 2: CHANGING FIRST-PITCH PATTERNS

No, this is not a Pitch FX essay, where we try to tell you what's changed in pitch selection and how this has sliced or diced an ever-so-crucial 35-run range across offensive performance.

This is a much more straightforward (but rarely if ever exposed) set of active comparisons that will (hopefully) make you think about what's been changing in one of the crucial statistical subsets in the game--namely, those plate appearances that begin and end with the first pitch.

With nearly a quarter-century of data, we can actually look at some relatively long-term trends, and that's just what we'll do.

The first thing we want to know when look at first-pitch data is whether the percentage of first-pitch plate appearances has been constant over that period, or whether it's changed. And, if it's changed, we want to know if that change looks random or shows a demonstrable trend. Go ahead and guess (if you haven't already looked at the chart below.)

Don't believe the trend you're seeing? You're not alone...no one today believes that Robert Young could have been a romantic lead in a lurid film noir, either.

Yeah, that's right. First-pitch plate appearances have dropped off by more than 30% since 1988. They were near 15% of all plate appearances then; now they barely scrape over 11%. That correlates reasonably well with the continuing rise in pitches/PA.

However, there's an odd fact that doesn't quite track with the trend displayed above. The percentage of PAs than end in walks (the stat we call BBP or BB%) has gone down rather than up since peaking in 2000, when the first-pitch PA pct. was making a rebound. Taking pitches and taking walks seem to be (for the lack of better term...) de-correlating.

First-pitch hitting is a good bit more successful than overall offensive performance: over the past twenty-four years, batters who hit the first pitch had an OPS+ of 127 with respect to the overall hitting levels. But once again, we need to look at any trends in that data to see if it tells us anything unusual.

Even Dogman Tony, the semi-clueless anti-hero of the noirish hobo documentary Long Gone (2003), is unable to explain why hitters are doing so much better over the last decade when they hit the first-pitch.

And here again, there is a rather astonishing progression. For reasons that we may not be able to identify,  overall performance on the first pitch took more than a tidy leap upward in 2001. Whereas the previous thirteen years had produced a 122 OPS+ for these PAs, the next eleven years have shifted a gear, with the aggregate OPS+ rising to 134 from 2001-2011. It's been at its highest point over the past three years, even as overall offense is falling. (As a matter of fact, the OPS figure for first-pitch hitting has fallen since 2009, just not as much as the overall offensive levels have.)

But we get another mystery when we couple this data with the first-pitch PA percentages in the first chart. If hitters continue to do well on that first pitch, why are their first-pitch PA percentages declining? Shouldn't they start to go up? But as those percentages have dropped, the OPS+ for first-pitch PAs has risen to its highest point. Does that mean that hitters have somehow gotten better at determining which first-pitch plate appearances are the optimum ones to hack at?

Contrary to popular belief, this bunt attempt does not represent the final
plate appearance in the career of Carlos Delgado...
Not sure that we can separate cause from effect on this one without a much more detailed data breakout, but before we move on to one possibly relevant factor, let's see if we can inject some fear and loathing into the numbers crowd. Anyone out there know the percentage of plate appearances where batters successfully execute a sacrifice hit? C'mon, take a guess. We have all spent a lot of time moaning about one-run strategies and their impact on run scoring, so you'd think everyone would have this figure at their fingertips.

Give up? OK, here it is: over the past twenty-four years, sac hits have accounted for just a bit over nine-tenths of one percent of all plate appearances. That's 0.91%, to be exact.

Now, of all those sac hits, what percentage of them occur on the first pitch? Please, take a guess. Of course, this data has to be front-loaded, because virtually no one will risk bunting with two strikes.

The answer: just under 47% of all SHs occur on the first pitch. Those SHs represent a little more than three percent of all first-pitch PAs (3.3%, to be exact.)

So the SH has been about 3.7 times more likely to occur on the first pitch than it does overall. And here's the scary part: that measure, along with the percentage of SHs on first-pitch PAs, have taken a noticeable tick upwards over the past three years. Last year, SHs on the first pitch were just under 4% of those PAs (stop the presses!!), and this meant that the majorly dreaded one-run strategy was being deployed almost 4.5 times as often as was the case generally.

At this rate, by 2020 we may simply have to ban the first pitch altogether in order to stop this trend.

Yeah, yeah, I know, my rim shot is not necessarily your rim shot. But have a shot of something before you look at our final chart, which shows the percentage of first-pitch plate appearances that result in home runs.

Who's that man behind our double-lined foul screen? Look closely and you'll see a pitcher who knows his way around underwear and is grateful that he didn't have to pitch in what Eric Walker (not Walt Davis!!) termed the "sillyball era"...

Looks to us that the scenario that includes the supposition that hitters have somehow gotten better at determining which first pitch is the one to swing at--a notion that just seems hard to defend based on any current type of study known to basement-dwelling man--is in some way a factor here.

Hitters sluggers HRs at 132% of the overall frequency from 1988-2000. That figure moved up to 146% from 2001-2011. The chart shows several yeas where the HR/PA rate was above 4% for first-pitch swingers, with that spike in 2009 representing a relative first-pitch HR frequency of 161%.

It's interesting how volatile this data is, and it's notable that there's been a falloff over the past couple of years. Pitchers may be starting to get this aspect of the first-pitch battle back under control, and we will find out one way or another soon enough.

Let's leave you with another of our patented wacky trivia questions. What pitcher has given up the most HRs on the first pitch? We'll post the answer to that soon.