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Can Bobby Witt Jr. improve his walk rate?

Low rookie walk rates do not doom a player for all time.

Detroit Tigers v Kansas City Royals Photo by Kyle Rivas/Getty Images

There seems to be a lot of wailing and gnashing of teeth about Bobby Witt Jr. having a rookie campaign that is not exactly what we were hoping for. It is hard to know just how to read his 2022 season. Baseball-Reference is the one most people seem to be freaking out about, they only have him at 0.8 WAR on the year. That is not great, but Fangraphs has him at 2.2 WAR, which for a 22-year-old rookie seems pretty good. For today I am going to avoid delving into his concerning defensive issues, and instead focus on his concerning on-base-percentage.

Bobby’s paltry .292 on-base rate is not what any Royals fan wanted to see this year. While he has never been an OBP machine, Witt did have better rates than that in the minors. His first stint, while in rookie ball, was the worst at a rough .317 OBP, but after that he posted a .369 in Arkansas and .352 in Omaha. The projections systems all had him in the low .300s, with ZIPS highest at a .323 rate going into this season. That made me wonder several things, but the main thing is what happens after a rookie season to walk rates. Witt’s walk rate was 9% in AA and AAA, but has been right at 5% so far in the majors. If Bobby had a 9% walk rate right now, his walks would be at 49 instead of 27, and if all of those replaced outs (they wouldn’t) his OBP could be as high as .333, which I think would have changed the read on this year dramatically.

To see what a realistic expectation for Jr’s walk rate going forward, I went and pulled rookie walk rates over the last decade. Then I compared rookie year rates to rates going forward. I did not want to go back too far because the strikeout and walk rate environments have changed so much in recent years. This can be done directly, but there are a lot of rookies who only barely make it to the pros, and then disappear never to be heard from again. Comparing Witt to all rookies equally - even those that wash out quickly - just seemed wrong. Instead, I divided players into those who improved walk rates, and those who did not after posting a poor walk rate (6% or below) during their time as a rookie, so I am thinking of this as probabilistic rather than trying to make an expected value that should be the center of the distribution next year.

About half of the nearly 200 poor walk-rate rookies over the last decade, after removing current rookies who don’t have post-rookie season data, showed some improvement in at least one season after they exhaust their rookie status. Some of them are still in their second or third year and could develop over time too. From there I looked at how much they improved the year after their rookie status is up, and what their best walk rate in any season was. In all cases, I required at least 200 plate appearances to look at any walk rate based at least in part on the statistical stabilization rates from Fangraphs (I stayed a bit conservative from a sample size perspective). The average rookie walk rate was 4.66% for this bad walk rate group, and the average for those who later improved was slightly higher at 4.87%, very similar to Witt’s rate currently. A larger proportion of the rookies who walked under 4% of the time just never made it very long, which is unsurprising. The next season, those rookies that improved at some point in their career had an average walk rate of 6.58%, so an increase of 1.71% from the average rookie rate. At their peak, the average jumps to 8.62%, an increase of nearly 4%.

Based on this, there is at least about a coin flip chance that Bobby is going to improve by a significant amount in the walk rate category. I think the chance is actually higher than a coin flip based on pedigree. If you look at the players who never improve, a lot of them are fringy prospects rather than top 100 guys like Bobby is. In my opinion, he looks a lot more like the Manny Machado, Brian Dozier, and even Zack Cozart types on this list than the Pat Valaika, Christian Villanueva, and Paulo Orlando types. There are players like Tim Anderson in the never posted a decent walk rate category, which has really capped his ability to be a top-end player, so I am not guaranteeing anything, but I do have a couple of comps that came up at a young age like Witt that we can explore. Again, all numbers require at least 200 plate appearances to qualify.

Nolan Arenado had fairly low walk rates in the minors, lower at all most every level than Witt’s in fact. His first full year was at age 22 and he walked only 4.5% of the time. His career walk rate is 7.9%, and he regularly put 9 and 10% rates up for a while before falling back in to the 7s and 8s the last few years.

Marcell Ozuna is similar, walk rates are lower than Bobby’s in the minors and then made it to the majors at 22 to post a 4.5% rate. His career rate is also 7.9%, but has posted rates as high as 14.2% in the 2020 shortened season.

Billy Hamilton’s walk rate was up and down a lot in the minors, again came up at 22. He was pretty volatile in the majors as well, but has a career 7% walk rate and peak of 9.1% rate.

Manuel Margot struggled to walk in the minors above low A ball, and then across his 21 and 22-year-old seasons walked only 6.2% of the time. His career mark is 7.2% and he is regularly in the 8s now.

Wilin Rosario would be your counter-example, but he walked less in the minors and as a rookie than Witt has. Still, there are players who come up young and the walk rate stays very low like Rosario’s has.

After staring at spreadsheets for longer than I should have, I think our expectation should be for Bobby to walk at a higher rate basically every year going forward, but probably never for him to be a consistently great walker. I am a little concerned that his walk rate in the second half this year has actually gone down from 5.4% in the first half to 4% after the All-Star break. It will be interesting to see what the projections systems have in the off-season as their expectation. My guess is that in his peak years Bobby is going to be more of a 7 to 9% walk rate with OBP rates that are in the .325 to .350 range.

In general, I would say that I am less pessimistic than the average Royals fan right now with respect to Witt Jr. I still expect him to be better defensively (I will save this for another day) and, as I just went through in detail, to improve at walking and getting on base. Everything else has been there in the rookie season, and I am expecting his peak power numbers to be very good, so I still think you are looking at a guy who will produce 4+ WAR regularly in his peak years. You don’t have to buy what I am selling, but I think the Royals have a cornerstone piece for their team in Witt, and I would still be pushing to sign him to a longer-term deal if I were working for the Royals.