Taijuan Walker Is Starting to Get It

It’s the middle of August, and the Arizona Diamondbacks find themselves in the thick of the National League Wild Card chase. As it stands today, the D-Backs are in control of the second Wild Card position behind the Colorado Rockies. Arizona’s success has come on the strength of their starting pitching, which has accumulated the third most Wins Above Replacement in Major League Baseball, according to FanGraphs. One of their best starters this year has been longtime object-of-attention Taijuan Walker, who is our topic of discussion today.

Walker, who was acquired last offseason in an interesting trade involving Jean Segura and Mitch Haniger, has been considered a potential ace since his days as the eleventh ranked prospect in Baseball America’s 2014 edition of their Top 100 list. Now, after plenty of injuries, home runs allowed, and a trade, it seems that Walker is beginning to unlock some of the potential that earned him that pedigree back in 2014. While injuries are a big piece of the Taijuan Walker puzzle, his baseball card shows that he gave up a lot of home runs when healthy. Here is an interesting graph to consider:

It’s no surprise that there is a strong correlation between fly-balls allowed and home runs allowed, but what makes Walker’s season so compelling is that he has corrected his home run problem on the basis of decreasing the number of fly-balls he’s allowed. Many analysts looking for the kryptonite in the Fly-Ball Revolution have identified rising fastballs as a fly-ball (and subsequently, home run) suppressor. To that degree, let’s look at how Walker located his fastball in 2015, his most healthy season to date:

The fastball was mostly concentrated in the middle of the strike zone, and it led to instances such as this:

Naturally, opposing batters like Josh Donaldson were all over those mistakes in the middle of the zone. Walker was torched to the tune of 1.33 HR/9 (and 1.81 last year). Of course, we also know that putting lift on pitches that spin as much as fastballs do is more difficult when the pitches are located up in the zone. To Walker’s credit, this is where he is concentrating that fastball this season:

It’s done wonders for Walker, and his fly-ball rate has dropped dramatically, as you’ll remember in our first graph. Here’s masher Anthony Rizzo popping up a high fastball from Walker this year:

Of course, if Walker is cutting down on the number of harmful fly-balls he allows, the overall distribution of his batted ball profile (between pop-ups, line-drives, ground-balls, and fly-balls) is going to change. Thankfully for Walker, it seems that he is inducing enviable contact:

As long as Walker can keep that fly-ball rate low (preferably below the 35% mark) and his grounder rate high (preferably above the 45% mark), he’s going to be in business. We know that Walker throws a decent splitter, so he will always get a fair share of ground-balls from that, but he has made a change in his arsenal this year to increase his grounder rate while maintaining his strikeout rate.

Walker’s strikeout pitch has always been the fastball we’ve already discussed, so having a low 90s cutter has always seemed a little redundant. Walker decided to scrap the cutter, which he located here…

…for a low-to-mid 80s slider, which he’s throwing here:

That slider is a more compelling pitch, and as of today it’s producing a 52.9% ground-ball rate and 23.5% fly-ball rate. That’s exactly what Walker wants and needs!

Taijuan Walker probably isn’t a number one starting pitcher, but the expectations placed upon him as a prospect were probably unfair to begin with. He’s on pace for the best season of his career, and there is potential for Walker to settle in as the third starter in a competitive rotation. Arizona paid a high price to acquire Taijuan Walker, but thankfully for them, he will not be a bust as long as he stays healthy.