Archie Bradley, Taijuan Walker, and Four-Seam Fastballs

It’s been fun profiling a couple of upcoming spring battles lately. There’s going to be some kind of rotation battle between some young, talented starters, and it’ll be intriguing to see how all of the infield pieces fit together. Avoiding the bullpen has been purposeful to date given the team might not be done adding there (more acquisitions today!), but the outfield and catching positions are probably what they’re going to be. And for all the questions about Yasmany Tomas, who’ll catch the most, and Jake Lamb versus lefties (again), the biggest issue facing this team is very familiar: starting pitching. And, we can zero in even further as it pertains to the future of the Diamondbacks: can Taijuan Walker and Archie Bradley become highly productive young pitchers?

I really don’t want to belabor this point any further — someone’s going to the bullpen (or the minors) this season from the group of Bradley, Patrick Corbin and Shelby Miller. I’ve written about it twice already, so let’s consider this “established” for today, even if you’re inclined to disagree. For a bunch of reasons, I think that’ll end up being Bradley to the bullpen — whatever, that’s not really here nor there for today. But you’ll notice that I didn’t include Walker in the group that’s on the bubble. Perhaps that’s a little curious in its own right, but for me, he’s going to stay in the majors and in the rotation as the D-backs gave up plenty to get him. They’ve invested, they want to reap the rewards of that investment, and the best way to do so is to make Walker a more consistently good starting pitcher.

If we’re talking about demoting Bradley, should we be considering demoting Walker? Let’s take a look at their 2016 seasons by game score, a year in which Bradley made 26 starts (5.02 ERA, 5.13 DRA) in his age-23 season while Walker made 25 starts (4.22 ERA, 4.27 DRA) in his age-23 season.

While Walker’s ERA and DRA were clearly better than Bradley’s, his average game score (48.2) was only one point better (Archie averaged 47.2). Neither mark is especially good, but for all of those great starts for Walker, he had some that were absolutely horrific. Bradley didn’t have the high-highs, but avoided some of the low-lows. Both clearly have some growing to do, and consistency is a big piece of the puzzle.

I should apologize for burying the lede, but here it is: both have had trouble with their fastball. If you’ve watched any of Archie Bradley’s work over the last two years, you’ve taken notice. Walker’s issues aren’t perhaps as bad, but he’s had a hell of a time keeping the ball in the park as he given up 52 home runs in 54 starts over the past two seasons. By my count, 28 of those home runs have come on four-seam fastballs. Meanwhile, Bradley can’t throw his where he wants to either, and both have had significant issues with the heat from time to time. We’ve seen starts where Bradley is racking up low strikes and Walker is blowing hitters away with them up in the zone. But we’ve also seen plenty where the fastball isn’t sharp, it’s not thrown for strikes to get ahead, and it catches a little too much plate. Sure, this happens to every pitcher from time to time, but it’s happened more than enough to these two in their young careers.

Both Bradley and Walker have the ability to run their fastballs up to the plate in a hurry — Bradley reached 96.9mph last season while Walker touched 98.4mph — but there’s clearly more to a fastball than velocity. I decided to take a look at all qualified starters that threw a four-seamer in 2016 to get an idea of how the young D-backs’ fastballs measure up to larger sample. With 70 pitchers under review, here’s how Bradley and Walker’s four-seamers stack up:

Both Bradley and Walker have fastballs that would be described as “jumping fastballs” based on the work of Max Marchi, who now works in the Cleveland Indians’ analytics department after doing great research for Baseball Prospectus. Both have above average velocity and both have above average vertical movement (or “rise”). Walker has a touch more horizontal movement on his four-seamer than average while Bradley is about 3/4″ below average. Take a look at both fastballs in action below.

Bradley’s strikeout of Chris Heisey comes on a 94.1mph fastball at the knees on the inside corner as it just nips the edge of the strike zone. Walker strikes out Jorge Polanco with a 94.2mph four-seamer that’s up and out of the zone. Heisey takes and Polanco whiffs, but both pitches show arm-side run with good velo. Bradley’s fastball has enough “rise” to catch the bottom of the zone while Walker’s has enough “rise” to stay out of the zone.

In fact, how they use their four-seamers points to a great divergence. Walker’s disposal of Polanco above isn’t a misrepresentation of how he likes to use the heat. Here’s his four-seam heat map from 2016:

And here’s the same heat map for Bradley who seems to consistently use his four-seamer in a particular way:

Walker clearly doesn’t mind using his fastball up as he challenges hitters regularly. Meanwhile, Bradley has a clear plan of attack, trying to keep the fastball down and to his arm side. Though they have similar fastballs in terms of movement and velocity, they certain go about using them differently. One can see where Walker can get into trouble with the long ball if/when those fastballs up in the zone get hit hard — they’re in a prime location to travel a long way. For Bradley, he misses the zone with the heat regularly, as he’s consistently trying to nip a small part of the strike zone, usually missing off the plate. Both flirt with disaster, just in different ways. Walker has been prone to the homer, Bradley the walk.

This wouldn’t be such a huge problem were it not for the fact that both young righties rely on their four-seamers so often. Here are the top five qualified starters for four-seam fastball usage, with Bradley and Walker thrown in at the bottom:

Bradley leans on his four-seam fastball a ton while even Walker would rank in the top five among all qualified starters if he had, well, qualified for the pitching title. Both throw their four-seamers a lot, placing extra pressure on the pitch. For Bradley, he doesn’t have a useful third pitch, forcing him to throw his four-seamer a bunch, then mix in the occasional curveball. Meanwhile, Walker relies on the fastball to do most his work, mixing in splitters and curves. Though Walker does mix things up more than Bradley, both pitchers can be prone to hitters hunting fastballs because they know they’re going to get them.

With the Diamondbacks staking so much hope on this pair of right-handed youngsters, and those youngsters’ reliance on the four-seam fastball, it’s critical that both pitchers take a step forward with their primary heaters. Best of all, the two can learn something from one another. Bradley might be well-served to challenge hitters more frequently with his fastball, using it up in the zone more and trying to get it in on the hands of right-handed hitters or up and out of the zone to lefties. Meanwhile, Walker may benefit from trying to locate a few more four-seamers down in the zone and on the corners. That’s not an easy task for either pitcher, but both need to make improvements with the four-seam fastball, especially if they’re going to keep relying on the pitch to the lion’s share of their work. As we watch both pitchers get to work in the Cactus League, we should keep a close on eye on the location of their four-seamers to see if adjustments are forthcoming or if they’ll stick to the script.