Christian Walker Might Be Due For Positive Power Regression

I was having a random conversation with Jack a few days ago comparing Kevin Cron to Christian Walker, specifically how Cron seems to have a leg up on Walker due to his swing seeming to be more flyball friendly. Then I stumbled upon something that was REALLY intriguing to me:

Christian Walker has the lowest rate of homers per barrel in the MLB.

Among MLB hitters with at least 10 barrels (the minimum Statcast would allow me to set), Christian Walker is tied with Mookie Betts for last with only 40%. Amusingly, both batters have 10 homers on 25 barrels (meaning one of Walker’s homers didn’t count as a barrel per Statcast). This seems really strange to me when you consider the following facts:

• Christian Walker is 25th in Barrels/PA and 22nd in Barrels/Batted Ball, out of 350 hitters
• Average exit velo: 94th percentile
• Hard Hit%: 97th percentile
• xSLG: 86th percentile

All of these things are suggesting that Walker has monster power. Which, he does. Yet, can you believe that it’s the middle of June and he only has 11 homers despite playing nearly every day? Just on the Dbacks, Eduardo Escobar (17), Ketel Marte (17), and Adam Jones (12) all have more homers than our slugging first baseman with monster power. For the MLB as a whole, there are 60 hitters with more homers than Christian Walker. This just doesn’t make a lot of sense, does it?

So I decided to do some digging. The first thing I looked at: is this a repeatable skill? I couldn’t find much research on my own, so it seems like I’m stumbling into new-ish territory (I’m not the first person to look at this). I put together Statcast data from 2015 through 2019 and compared batters year over year (e.g. comparing 2015 to 2016, 2016 to 2017, etc.) to see if this is a “skill” (e.g. it’s repeatable) or if it’s just noise:

Well, that was easy: no, this does not appear to be a skill. With an R^2 below .05, this is pretty much noise.

So what does this mean? It means that Walker has been on the “unlucky” side of things when it comes to barrels and we should expect him closer to average going forward.

But we’re not stopping there. I decided to look more into the relationship between homers and barrels and it’s pretty easy to see where Walker is struggling.

To start, here is a chart showing how homers per barrel has varied during the Statcast years:

There is some variance to this metric which is rather interesting when you see the next two graphs. The samples here are extremely large - we’re talking thousands of data points each season - enough such that random variance should be very minimized. I don’t have an answer to this variance - it could very well be that the definition of barrels is changing from year to year. However, you can see how low Walker is compared to the league average.

Barrels are pretty easy to define. They need to be hit hard enough (somewhere over 95 MPH, roughly), and at an ideal range of launch angles. I can’t give just a simple range of numbers, because the launch angle for a barrel depends on the velocity of the hit. But the overall theme is simple: barrels are all about launch angle and exit velocity.

You should know where this is going:

Considering how good Walker’s power percentiles were above, it should be no surprise that he hits barrels nearly 2 MPH faster than average. And yet, shouldn’t this mean more homers for Walker, not less? Well, yes, except for the second half of the equation: launch angle. And this is where Walker is lagging:

This makes a lot of sense. You can hit the ball as hard as humanly possible but if you don’t get enough launch angle, it’s not going to clear the fence. And this has been Walker’s problem this season. Walker has a high number of barrels but a large number of them have been a low launch angle, limiting Walker to doubles instead of homers.

Some have also been some “bad luck”, such as this 424 foot double off the wall in dead center:

Or this 419 foot double in Colorado:

Now, this is part of the game of baseball. Sometimes a homer in one park is a double in another park. But the general idea is that this is not likely going to be a common “problem” for Christian Walker going forward.

The baseball community is still diving hard into launch angle research, but the general consensus is that it is not a very “repeatable” skill, except at the extremes (either < 0° or > 30°). And this is validated by the graph I showed earlier, where the Year 1 to Year 2 relationship between homers/barrel was just noise. Consider how there was very little variability in the launch angle and exit velocity charts, yet there was a ton of variability in the HR/barrel chart. That shows how strong the “randomness” factor plays into hitting a home run (environment, ballpark, weather, spin, etc.).

Both launch angle and exit velocity are going to vary and Walker is already shown to be consistently at the high range for exit velocity; it’s only a matter of time before a few breaks go his way and he goes on a homer tear, much as he did to start the season.

And what’s more, Statcast is buying on Christian Walker, too:

• wOBA: .344
• xwOBA: .366
• xwOBA on contact: .486 (94th percentile)
• SLG: .476
• xSLG: .522

That’s a lot of upside that Statcast is currently calling for Christian Walker. After his early strong start, the league adjusted and found a hole, causing a massive slump... but it appears that Walker has rebounded fairly nicely:

He’s also settled in to a walk rate just below 10% and has managed to keep his strikeout rate under 30%. And despite the very prolonged slump, he’s still sitting on a 107 wRC+ with some power upside if the regression comes through. We could be looking at a hot summer from Christian Walker.