How Worried Should We Be About Javier Baez’s Plate Discipline?

Javier Baez spent about two months at Peoria last season, crushing baseballs to the tune of a .432 wOBA over 235 PA’s. He hit a few baseballs clear out of the stadium that many Cubs prospect writers are still talking about as they discuss various top prospect lists. Javier Baez has loud tools that earn him a spot as one of the best prospects in baseball, and there is no arguing that.

That said, there is a glaring flaw in Baez’s current game: his abysmal plate discipline. Prospect writers and Cubs fans alike will all tell you that his 3.8 BB% and 20% K% at Peoria last season are nothing to worry about, that any prospect as gifted at the plate as Baez will turn things around (This refrain was common early in Josh Vitters’ career, too). There have been many excuses for the poor discipline (“he’s hitting everything he sees! Why take a pitch?”), but most of them ring hollow to me. I’m wary of the overall prognosis that elite prospects eventually improve their plate discipline, and therefore Baez will too, so I’ve decided to dig into the track records of prospects with comparable plate discipline. After all, if so many top prospects eventually improve their plate discipline, then that should show up very clearly in the data.

To conduct this study, I have compiled a list of 652 unique position players to be ranked as a “Top 100 Prospect” by Baseball America since 1990, complete with their plate discipline numbers at every professional level they played at. I am running under the assumption that the characteristics necessary to be ranked a top prospect have not changed much in the last 23 years, and that most prospects on my list possessed at least a few plus tools, if not a plus-plus tool like Baez’s bat speed.

Of those 652, only 77 posted a walk rate below 5% at any A-ball level, and only 16 posted a rate below 4% in A ball.


The set of top prospects I wanted to look at first was the set of all top 100 prospects to post a sub-5% walk percentage at A-ball in a sample of more than 200 PAs. This gave me a set of 36 prospects, only 12 of which had a K% over 18%. Many players in this group went on to have modestly successful MLB careers, and the group as a whole combined to produce 2.0 BWARP/650PAs, a 4.78% combined BB% and a 16.31 K% at the major league level. These 36 prospects can be broken down into 3 distinct groups, with the highest ranking they reached in parentheses:

The Good: Jose Reyes (3), Alex Rios (6), Howie Kendrick (12), Javy Lopez (17), Preston Wilson (43), Carlos Lee, Erick Aybar(39), Brian McCann (44), Christian Guzman (68), Garrett Anderson (93), Juan Uribe (94).

The “At Least They Played in the MLB”: Corey Patterson (2) , Michael Barrett (6), Alcides Escobar (12), Jeff Francoeur (14), Derek Bell (15), Jeremy Reed (25), Cesar Izturis (67), Greg Colbrunn (85).

The Busts: Derrick Gibson (13), Chris Marrerro (27), Josh Vitters (so far) (43), Earl Cunningham (44), Ryan Harvey (65), Tony Blanco (87).

Below is a table of the average “progression” of the walk rate of each group. For example, the A –> A+ column is the average of each group’s A-ball walk rate subtracted from their A+ walk rate. NOTE: These are not percentage increases in BB%, but rather the difference between two percentages.

BB% Progression A –> A+ A+ –> AA AA –> AAA AAA –> MLB
“Good” +1.91% +0.14% +0.23% +0.17%
“OK” +1.03% +0.81% -0.13% -0.683%
“Busts” +2.11% -0.76% -0.71% -1.58%

The “Good” group walked at a 5.36% rate in the MLB, which represents an average increase in walk rate of 1.58% between A-ball and the MLB. Most of the gains were achieved in the jump from A-ball to High-A, after which they remained steady for the rest of their career. This group also struck out in only 13.9% of their plate appearances, much better than league average. The middle group has some decent ball players in it, and the group as a whole walked at a 5.47% rate in the MLB and struck out in 17% of their plate appearances. This group also had trouble providing value while in the majors, combining to produce only 0.74 BWARP/650 PAs. Though he had only 86 PAs in High-A Daytona, Baez appears to fit in best with the “Good” group, as he he increased his walk rate by almost 2%.

However, it is important to note that the players in the “good” group were mostly see-ball hit-ball type players with excellent hit tools who pounced on pitches early in the count, never falling deep enough into counts to strikeout or walk all that often. Javier Baez, according to most scouting reports, is not this type of hitter. Baez has trouble with both pitch selection and making contact with the strikes he does swing at. His short stint at Daytona last season really showcased why so many have called his hit tool into question.


I have a second set of top prospects I’d like to look at, and these are players who walked in less than 5% of their plate appearances and struck out in more than 20% of their plate appearances across A and A+ combined (I don’t want to look at just A+ numbers because Baez had only 86 PAs there in 2012, and I will update this post once he has passed the 200 PA threshold in Daytona). There were only 14 players in this sample, and only three (Javy Lopez, Preston Wilson, and Christian Guzman) had much of a MLB career.

Players in this group: Javy Lopez (17), Preston Wilson (43), Christian Guzman (68), Joel Guzman (5), Derrick Gibson (13), Angel Villalona (33), Earl Cunningham (44), Wilin Rosario (49), Greg Halman (57), Ryan Harvey (65), Chris Davis (65), Dane Sardinha (74), Cesar Puello (77), Hector Gomez (95).

Eight of those 14 names busted outright, one took three years off of baseball because he probably killed someone, and the book is still out on Rosario and Davis. This is by no means a good group of ball players to be compared to, and all but Wilson saw only marginal increases in their walk rates between A+ and AA.


From the two sets of top prospects I looked at, there was very little to suggest that top prospects with poor plate discipline improve very often. Preston Wilson was really the only top prospect who had poor plate discipline in A ball who showed considerable improvement in their plate discipline throughout the minor leagues and into the majors. So while top prospects do often improve their walk rates, it is often by less than a percentage point or two. This certainly invalidates the common line that top prospects easily improve their walk rates as they progress.


How concerned should we be about Javier Baez because of this?

I may be biased after watching Cubs prospect after prospect come up through the system and busting because they swing at every pitch they see, but I am concerned about Baez’s approach at the plate. Striking out in over 20% of your plate appearances at any A ball level is cause for concern, regardless of whatever your walk rate or ISO or OPS is there. When you factor that in with the reports of a questionable hit tool and the inability to walk, you have the makings of a player who is going to get eaten alive by pitchers who can command their breaking stuff and work advanced pitch sequences against a batter. And even if Baez’s raw power and natural abilities do let him get to the majors with such an approach, he’s likely going to be getting on base at a rate that hovers near .300. It takes a bunch of power and BABIP luck to overcome such an approach.

Luckily, Baez’s tools are so special that he’s got more than a fighting shot to significantly improve his plate discipline. Baez has tremendous bat speed that generates enormous power, which BP’s scouting team recently ranked as one of the best in the minors. Baez should be able to allow pitches to get very deep in the zone before he has to start his swing, affording him precious extra milliseconds to read pitches. If he’s able to improve his pitch recognition, I see only one reason why he wouldn’t be able to post very strong plate discipline numbers, and that is if his hit tool fails to develop. Baez may struggle for a few years in the minors as he faces more pitchers with legit stuff, but he has all the physical tools to develop into a selective hitter. And selective hitters with his power are impact players of the highest degree. So while I’m not giddy over his first-pitch homers in spring training like most Cubs fans, I’m still very excited to see Baez develop into a MLB quality hitter.

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