What exactly is plate discipline? Go ahead, give us your definition. You could likely ask ten different baseball fans what their definition of plate discipline is and you could very well receive ten different answers.
A little over a year ago, when I was just realizing that plate discipline was not the same as patience, I asked three different scouts that I had contact with to kindly define plate discipline for me. I received three different answers. Sure, some of what they said agreed with each other but each scout had a different complete take on what the term plate discipline means.
When I asked some of my friends, who happen to be casual baseball fans, what they thought plate discipline encompassed they all tended to agree that patience was a good answer to the question. While patience is a component to plate discipline it alone does not equal plate discipline. In fact, one can have patience without having plate discipline.
One of the scouts referenced San Diego Padres' outfield prospect Jaff Decker's when defining plate discipline to me. Jaff Decker had just finished his third season in professional baseball and I knew exactly who he was. I honestly thought he would tell me about how many walks he took and how he had a .513 on-base percentage as an 18 year old in 2008 but I was wrong. He went on to tell me how Decker had extreme patience but lacked overall good plate discipline. I was a bit confused. Decker had never posted an OBP below .374 in this those years.
The scout went on to talk about how Decker would get himself into two-strike counts before getting the bat off of his shoulder, simply to try and "work the count." I asked him "what's wrong with him working the count?" He said "nothing, but when you let two hittable pitches go without offering at least one I cannot make the claim that you have good plate discipline."
That scout's answer made me look at plate discipline in a completely different light. I started realizing that, while Adam Dunn would draw 100+ walks per season, he actually lacked proper plate discipline. And, although it took Albert Pujols eight seasons to reach 100 walks, he had more plate discipline than just about anyone in the game.
While I was watching the Rays game on Tuesday night I was having a conversation about this very subject with a friend of mine. He is a casual fan and asked me to give him an example of a hitter who exemplified good plate discipline. Fortunate enough for me he was a Rays fan and new the roster very well and they happened to have one of the most disciplined hitters in the game in Ben Zobrist.
Simply making the pitcher throw more pitches does not mean you have good plate discipline. Yes, again, patience is a part of plate discipline but getting yourself into a good hitter's count has more to do with good plate discipline than taking pitches does.
One of the things the scout told me was that a hitter must not swing at a lot of pitches outside of the zone. Every hitter will do it at times but limiting your swings on pitches that are balls is key.
Since Zobrist started receiving regular playing time in the second half of the 2008 season he has never posted a below average O-Swing%. Our very own Steve Slowinski estimates that an O-Swing% at 30% is average. Since 2008 Zobrist's has never been above 25.6% and PITCHf/x says it has never been above 24.1%.
One of the best ways to get yourself into a hitter's count is to make sure you swing at the hittable pitches and make them count. There are few people better than Ben Zobrist at doing this.
Ben Zobrist currently leads the American League in walks with 11 in 13 games but if he sees a first pitch that he likes he is going to swing at it. That is what the scout was referring to when he gives a hitter a good plate discipline grade, not letting the hittable pitches go to waste. Ben Zobrist owns a career .369 batting average and .656 slugging percentage on first pitches and 18 of his 74 career homeruns have come on first pitches. Pitchers who read scouting reports have to know by now not to throw a "get me over" first pitch strike to Zobrist. They must try and locate better and this increases the chances of a pitcher throwing a pitch off the plate.
Zobrist does not stop at the first pitch. Traditional pitch counts where a pitcher must throw a strike are at 2-0, 2-1, and 3-1 counts for fear of falling behind the hitter and walking him.
Zobrist owns a career .341 batting average and .659 slugging percentage in 2-0 counts, .360 batting average and .596 slugging percentage on 2-1 counts, and .379 batting average and .679 slugging percentage on 3-1 counts.
Zobrist is disciplined enough to get into a hitter's count, patient and disciplined enough to draw a walk, disciplined enough not to swing at too many pitches out of the zone, and disciplined enough to swing at the hittable pitches coming his way.