Plate Discipline: Better or Worse? And Is it Lenny's Fault?

The Nationals this year have earned a reputation for poor plate discipline. Asked for a scouting report on the Nationals, Jamie Moyer, one of the game's smartest pitchers, said, "Overaggressive. Sometimes." Most Nationals fans no doubt thought the second word was thrown in just to be polite. (Moyer's also a pretty nice guy.)

Some, Chris Needham most prominently, have argued that a team-wide over-aggressive approach is behind the team's poor offensive performance, and that it's an approach that is actually being taught by Lenny Harris. The theory goes like this: Lenny was a career-long pinch hitter. As a pinch-hitter coming off the bench cold, the risk of striking out is much greater. So his approach was to sing at the first pitch he could reach and slap at it. It's a terrible approach for creating runs--you will hardly ever walk or hit for extra bases, the two things that generate the most scoring--but it's not a bad idea if you're coming up cold and just trying to avoid making an out to keep the inning alive. So, the theory goes, this is what Lenny is teaching to the Nationals--hence their poor plate discipline, lousy power numbers, and generally terrible offense.

And there certainly has been some evidence to back the theory. When the Nationals first acquired Wily Mo Pena, there were a number of quotes from Lenny about how he was working to transform Pena's swing to get him to go the other way. Chris did a piece on Zimmerman back in April focusing on his approach that appeared to offer more evidence.

I thought it might be interesting to look closer at the data on plate discipline and first figure out, in fact, are the Nationals who are under-performing taking a more aggressive approach at the plate? And if so, is it enough of a pattern to conclude that Lenny's teaching his slappy, pinch-hitting ways to the whole team?

My attempt at a smart, statistics-based analysis steals a bunch from a couple articles by David Appleman on Fangraphs.com. If you are interested, you can check them out.

The stats I'm looking at (available at fangraphs.com and baseball-reference.com) are:

• O-Swing% (OS%): the percentage of pitches outside the strike zone a hitter swings at. Appleman shows that this number tends to correlate strongly with walk rate (not a shock). MLB hitters range from 5 to 37%.
• Z-Swing% (ZS%): the percentage of pitches in the strike zone a hitter swings at. MLB range is from 55 to 80%.
  
• Zone % (Z%): the percentage of pitches a hitter sees in the zone. Obviously, the hitter has almost no control over what pitch the pitcher decides to throw, but this tells you something about the approach pitchers are taking. This correlates with HR/FB and walks, as more dangerous hitters tend to get piched around.
  
• Contact rate: the percentage of time a hitter swings and makes contact. This tends to correlate with strikeout rate--again no shock--and also HR/FB rate, as guys who are swinging for the fences tend to swing and miss more. MLB range is from 55-94%.
• Walk %: You know what this is. MLB range is from 3 to 14%.
• HR/FB: the percentage of flyballs that become home runs. For pitchers, this stat is mostly a function of luck. But for hitters, it's a more useful measure of power (though other stats like SLG and isolated power are certainly better).
  
• P/PA: Pitches per plate appearance. More patient hitters see more pitches. MLB range is around 3.1 to 4.4.

The tricky thing, there's no "ideal" degree of plate discipline or aggressiveness. Indeed, the optimum stats for any given hitter depends on what the pitchers are doing. It's possible to be overaggressive, but it's also possible to be too passive, as pitchers will start to jump out ahead with strike one every time if they know you're not likely to swing at the first pitch. We know it's good to take or spoil pitcher's pitches and it's bad to take or miss pitches in your wheelhouse. But we don't have stats for that--only some proxies that might hint at that.

Also, plate discipline is just one aspect of hitting, and these numbers won't tell us even close to everything we need to know to diagnose each hitter's strengths and weaknesses. But, we can try to get a sense of what if anything they are doing differently this year on plate discipline that might explain part of the situation. And we can try to get a sense of whether there are any team-wide patterns or not.

To keep the focus narrow enough to not overwhelm, I'm looking just at the most underperforming players and comparing their plate discipline this year to what they did in their best years. I also looked at Guzman and Flores, probably the two most pleasant surprises, to see if there's anything more to learn.

Felipe Lopez

	ZSw%	OSw%	Zone %	Cont %	BB%	HR/FB	P/PA
05	57.8	15.3	53.6	84.3	8.9	18.3	4.0
08	58.8	18.2	50.9	85.6	9.0	2.3	3.7

I compared Lopez's '08 numbers with his career year 2005 in the Great American Small Park. Lopez this year swung at more pitches both in and out of the zone, and pitchers apparently took advantage by giving him fewer pitches in the zone to swing at. But actually none of these numbers are terribly over-aggressive. Scroll down and you'll see guys like Milledge, Flores, and Pena swing way more. His 3.7 P/PA isn't a terribly low number either, though it too is down. The number that jumps out at you more is the cratering in HR/FB. The reality is that the 2.3% number in 08 is extremely low, but the 18.3% in 05 is a huge outlier in his career number, no doubt a GASP-inflated number. Bottom line, Lopez's plate discipline numbers are worse, but he has other problems.

Ryan Zimmerman

	ZSw%	OSw%	Zone %	Cont %	BB%	HR/FB	P/PA
06	61.3	23.7	52.7	80.6	9.0	11.4	3.88
08	61.2	25.5	53.1	82.9	6.2	9.8	3.62

Compared with his stellar rookie season, Zimmerman's swing percentage in the zone is almost identical, and if there's one number you'd expect to see up if Lenny is teaching an aggressive pinch-hitting approach, that's the one, and 61% ZS% is pretty darn selective in the zone. But outside the zone, he's swinging at too many--not a huge difference from 06, but he was swinging at too many then too. If you look at his spray charts and click on HRs, 2Bs, and FB outs from this year and 2006, you will see an increased tendency to go the other way. His contact rate has always been high and went up even more, but like so many his power is down significantly. One wonders if maybe pitchers have just figured out an approach to get him out that he hasn't been able to adjust to. Or does he just need to stop making so darn much contact and just try to hit the ball out more.

Wily Mo Pena

	ZSw%	OSw%	Zone %	Cont %	BB%	HR/FB	P/PA
06	77.1	35.8	47.5	64.1	6.8	14.7	3.54
08	75.6	35.8	48.3	68.6	4.9	5.4	3.62

Pena is now and always has been an incredibly aggressive hitter, going after as many pitches both in and out of the zone as any hitter in baseball and getting a very low percentage of pitches in the zone, which is a result of pitchers taking advantage of his weaknesses. Although his contact rate this year is up a tick, it's still really low, so if he's trying to improve his bat control and go the other way, he's failing miserably. And the problem is that if you are swinging and missing this much, you better do damage when you connect, but his 5.4% HR/FB rate belongs to a slappy middle infielder. Indeed, if you look at his spray chart (click the link and click on 'flyballs'), you'll see a lot of flyball outs to the opposite field. Click on HR, and they're dead pull shots. Actually, though, click on his 2005 season in GASP, and you'll see the same pattern. In short, any flyball he pulls is gone, so by definition flyball outs are almost all to the opposite field. I'm not sure I see evidence of him consciously trying to go the other way a whole lot more. He just seems to have lost the ability to get around on pitches. Maybe he is hurt.

Austin Kearns

	ZSw%	OSw%	Zone %	Cont %	BB%	HR/FB	P/PA
06	72.6	18.4	50.3	74.0	12.4	15.3	4.09
08	60.8	15.1	52.9	83.6	9.8	7.6	3.96

Woah, what's happening here? Kearns appears to blow up any theory that this team is struggling because of some team-wide commitment to a slappy, over-aggressive style. So far, no one really is swinging more at pitches in the zone (except Lopez, who I think we can agree wasn't doing anything anyone would coach him to do), but Kearns's swinging in the zone has fallen off a cliff. Related, pitchers are coming after him more. He's seeing a lot of pitches and making a ton of contact, but the power is zapped. Toggling through the spray charts, he went the other way no less in the GASP in 06 than he does now. These numbers would seem to suggest that Kearns needs to be far more aggressive, that he's taking pitches over the plate that he should be hammering. From my anecdotal observations, this is what I would have guessed.

Lastings Milledge

	ZSw%	OSw%	Zone %	Cont %	BB%	HR/FB	P/PA
07	67.2	32.0	47.6	76.1	6.6	17.1	3.82
08	67.7	31.2	51.9	79.9	6.5	10.7	3.91

Another life-long hacker, both in and out of the zone. But again from last year to this, there's no real change. Pitchers seem to be coming at him more, which seems dumb. He's seeing a few more pitches per plate appearance and making a bit better contact, but again his HR/FB is down. I'm going to guess that his current tear will continue long enough to close most of that gap so that by the end of the year these numbers look at least as good or better across the board in 08 v. 07.

Jesus Flores

	ZSw%	OSw%	Zone %	Cont %	BB%	HR/FB	P/PA
07	65.6	32.5	49.5	75.8	7.2	9.1	3.19
08	67.7	31.2	50.1	70.8	5.9	12.1	3.72

Flores is another real hacker. He sees a pretty low number of pitches in the zone, which is to be expected when you are swinging at this many balls. His contact rate is down, and his HR/FB rate is up, which would suggest that he's swinging more for the fences. If Lenny's teaching him to go away, this young hitter is ignoring his coaches.

Cristian Guzman

	ZSw%	OSw%	Zone %	Cont %	BB%	HR/FB	P/PA
05	64.2	22.8	58.4	83.9	5.2	4.4	3.19
08	62.7	26.8	53.3	88.6	3.9	4.7	3.10

I wanted to look at Guzman this year versus his awful 2005 season. One would think that a player with such different outcomes maybe made some big changes. But not really so much. He's going after slightly more pitches out of the zone as he's seeing fewer pitches in the zone overall (probably pitchers are pitching around him a bit, a laughable thought). The number that really jumps out is the contact rate is significantly up, and it was already fairly high. And indeed his K rate is way down from 16.1 to 12.7. These numbers would seem to back up the theory that he's just seeing the ball better since the Lasik.

So what does this all tell us? Maybe nothing. There are plenty of very aggressive hitters--Pena, Milledge, Flores, and Guzman. But no one really is more aggressive than they were in their better days, especially in the zone. Then you have Kearns, who seems flat out passive.

There is some evidence that Pena and Zimmerman are going the other way more and perhaps too much, as their power is down. But Kearns, Flores, and Milledge aren't going the other way significantly more than in the past.

Bottom line, I think a bunch of these guys are indeed too aggressive. I think you have some guys who have always been hackers who probably are who they are (Pena, Guzman). Some young guys are still learning (Milledge, Flores). You can probably blame Lenny for not getting these guys to make more progress than they have, but I don't see evidence that Lenny's teaching it that way.