John Jaso: Plate Discipline and Outcomes

Many A's fans were miffed when Jaso was acquired, as the team paid a high price in the name of prized pitching prospect A.J. Cole. After all, Jaso was coming off of a breakout season in 2012, with a 143 wRC+, 10 HR, and .850 OPS in only 361 PA. He had had a pretty good season in 2010 with the Rays, but that was followed by a virtually replacement level season in 2011, where he had an 85 wRC +, 5 HR, and a .651 OPS. That said, the A's had an offensive black hole at catcher last season, so anything was likely going to be an upgrade.

As before, I'm going to lift the groundwork for looking into plate discipline statistics right from prior articles:

While most stats take some time to normalize, research has shown that plate discipline statistics reach some level of significance after only 50 or plate appearances. These data are derived from two sources: Baseball Info Solutions (BIS) classifications or PITCHf/x. BIS is basically guys sitting down watching baseball games and classifying pitches. PITCHf/x is MLB's in-house pitch classification that relies on a neural network to decide what pitches are what. Essentially, a really fancy and expensive computer program designed for decision-making. After all this, there are 9 pretty useful statistics:

O-Swing%: The percentage of pitches a batter swings at outside the strike zone.
Z-Swing%: The percentage of pitches a batter swings at inside the strike zone.
Swing%: The overall percentage of pitches a batter swings at.
O-Contact%: The percentage of pitches a batter makes contact with outside the strike zone when swinging the bat.
Z-Contact%: The percentage of pitches a batter makes contact with inside the strike zone when swinging the bat.
Contact%: The overall percentage of a batter makes contact with when swinging the bat.
Zone%: The overall percentage of pitches a batter sees inside the strike zone.
F-Strike% - The percentage of first pitch strikes (BIS only)
SwStr%: The percentage of total pitches a batter swings and misses on (BIS only)

These are all pretty self-explanatory and describe the player's selectivity at the plate. With that, you also get league-average data that I have used here.

Since I much prefer PITCHf/x classifications, but BIS has two data points that PITCHf/x doesn't use, I've merged the data into one table that describes it all. The first seven columns use data from PITCHf/x, but F-Strike% and SwStr% come from BIS data. All data itself (and the above glossary terms) are from Fangraphs.

John Jaso plate discipline 2012-3, in percentages
	O-Swing	Z-Swing	Swing	O-Con	Z-Con	Con	Zone	F-Strike	SwStr
2012	20.5	56.1	38.0	69.9	90.5	84.8	50.1	57.9	5.8
lgAvg	29.0	62.2	45.3	63.6	87.3	79.6	49.2	59.8	9.1
2013	24.4	53.7	38.8	65.4	90.0	82.1	49.0	55.1	6.9
lgAvg	28.4	61.9	44.8	62.9	87.0	79.2	48.9	59.8	9.2

Note that league average rates for 2013 have been altered slightly to reflect additional data.

It's pretty easy to see why the A's wanted Jaso, blackhole of hitting suck at catcher aside: he is a disciplined hitter. He swings at fewer pitches overall than the average hitter does, and despite that, when he does swing, he makes more contact than the average hitter, both inside and outside the zone. Given his breakout last year, this approach going forward should serve him well. Except, that's not really what he's doing; in fact, he's doing the exact opposite (albeit still at a better rate than the league is). Compared to 2012, while he is swinging at basically the same number of pitches overall, he's swinging at lesser quality pitches. He is swinging at more pitches outside the zone, and fewer pitches inside the zone. This also comes with a slightly higher SwStr% and a lower F-Strike. On the bright side, the changes in contact percentage come almost exclusively from not making as much contact outside the zone (inside the zone he is making the same contact). So, if he can remedy the O-Swing issues (or maybe if it just stabilizes over time), he'll have reverted to what he was doing last year.

Obviously, it's not clear whether this is a conscious approach change, a product of coaching, or what. But, when you look back at someone like Chris Young, who is also new to the organization, you begin to wonder whether there is a coaching effect of being more aggressive on these two guys and that mucking with approaches that, at least in Jaso's case, were working for him.

Jaso's career numbers are somewhat of a jumble, seeing as he has had an up-and-down career. His career plate discipline stats are shown below:

John Jaso plate discipline, career, in percentages
	O-Swing	Z-Swing	Swing	O-Con	Z-Con	Con	Zone	F-Strike	SwStr
Career	19.8	51.8	35.8	70.7	92.8	86.7	50.1	56.5	4.8

If anything, Jaso's progression as a hitter have shown that he is simply getting more aggressive over time while maintaining better than average contact rates over his career. Rather than Davis' doing, then, it may be Jaso himself with a positive feedback mechanism going: he gets more aggressive, and more successful, and therefore decides to become more aggressive and so on.

There's not really a BABIP effect, but his batted profile does look significantly different so far than it has in the past. It's better to show it, so here's the table:

John Jaso batted ball profile, 2012-3
	GB/FB	LD%	GB%	FB%	IFFB%	HR/FB%	IFH%	BUH%
2012	1.64	25.4	46.4	28.2	7.1	14.3	7.8	0.0
2013	0.96	29.0	34.8	36.2	12.0	4.0	12.5	100.0

To orient you on the non-obvious ones, IFFB% is the percentages of fly balls (not just times made contact) that are infield fly balls, IFH% is the percentage of ground balls that are infield hits, and BUH% is the percentage of bunts that end as base hits.

There are some pretty significant differences there. The GB/FB and HR/FB ratios are significantly off, and the latter may be indicative of some unsustainable fly ball luck. Indeed, a 14.3 HR/FB% (especially for a mostly ground ball guy) is probably not happening again. That said, he's not been a ground ball guy this year, and has more flyballs and IFFBs to go along with a .324 BABIP.

In sum, Jaso is a little of an enigma. He may have changed his approach slightly, but that itself has led to far worse outcomes than would be expected. The question is whether those normalize to something akin to last year, or closer to average catcher territory.

I will have your gamethread later on today. It's Tommy Milone vs. Zach McAllister at 4:05 PST. And it won't be Angel Hernandez behind the plate. Woot!