On Tuesday, an MLB Network graphics designer made one of those simple, schadenfreude-inducing production mistakes that disturbs the smooth façade of the studio show, pairing the full-season stats of the starters in that night’s Tigers-Mariners game, Kyle Ryan and Taijuan Walker, with the headshots of the starters from an earlier Astros-Indians game, Vincent Velasquez and Corey Kluber.

Walker isn’t a bearded, Wahoo-wearing white guy, but from a performance perspective, the confusion is almost understandable. For the last several weeks, Walker, like Kluber, has been one of the best pitchers in baseball. In 2013, sabermetrician and Chicago Cubs consultant Tom Tango updated Bill James’s “Cy Young Predictor” with his own simple formula that more accurately reflects current BBWAA voting patterns (if not necessarily actual value to one’s team, although the two are closely correlated). Here are the leaders in Tango’s Cy Young Points since May 29 — a not-entirely-arbitrary endpoint, as will soon become clear.

Like most pitcher leaderboards worth paying attention to, this list includes Clayton Kershaw, as well as two other Cy Young winners, Chris Sale, and a number of starters who’ve had previous seasons that would have landed them on similar lists. But it also includes two pitchers in their first full seasons as major league starters: Seattle’s Walker and St. Louis’s Carlos Martinez, who vaulted to the top with 7.1 scoreless innings against Pittsburgh on Thursday.

Martinez, 23, and Walker, who turns 23 next month, don’t play in the same league, come from the same country, or speak the same first language, but their careers have moved almost in lockstep. Both pitchers began their pro careers in 2010 and debuted on Baseball America’s preseason top prospect list before the 2012 season — Walker at no. 20, Martinez at no. 27. Both made the majors in 2013. And both had to clear some early hurdles before blossoming this summer.

Walker, the larger of the two right-handers, had a trying season in 2014, suffering shoulder inflammation that kept him out of action from mid-February through mid-June, and then playing catch-up across four levels. He pitched only 38 innings in the majors, getting outs despite shaky control.

This spring, Walker was healthy and dominant, allowing only two runs in 27 exhibition innings, with 26 strikeouts and five walks. Then the real season started, and so did the mistakes.

“I think the expectations coming out of spring training were really high, because he was doing everything right,” says Seattle pitching coach Rick Waits. “And then all of a sudden his first couple starts he really struggled. And he really struggled with just location. That was the main thing, just too many balls over the middle of the plate, and some walks, and he got hit a little bit. It took him a while to react to that. I think it was a shock to him — probably a shock to all of us. It was, ‘Wow, how is this happening?’”

Walker entered his May 29 start against Cleveland with a 7.33 ERA in nine starts, including 23 walks in 43 innings. He’d had a pair of strong outings in late April, but he’d also failed four times to go further than four innings. With the team as a whole off to a slow start in a high-pressure season, Walker was likely one blowup away from a return trip to Tacoma.

“The first month and a half of the season, I didn’t have conviction behind anything,” Walker says. “And then I knew I had to turn it around, or I wouldn’t be pitching again.”

Instead of losing his grasp on the rotation, though, he had his best big league start: eight innings, two hits, no walks, and eight strikeouts.

“Something just clicked,” Walker says. “It just felt like everything was falling in place, and it’s really been working. And whatever happened, I was being more aggressive with the fastball, getting ahead, not walking people.”

Players’ explanations for their own success aren’t always backed up by the stats. In this case, though, the numbers completely corroborate what Walker is saying. Like many players who’ve moved from one performance extreme to another, Walker has benefited from better luck on balls in play. But the improvements in the outcomes that are largely under his control are even more striking.

From April 1 through May 28, Walker threw 23.9 percent of his pitches while ahead in the count, the seventh-lowest rate of 138 pitchers who threw at least 500 pitches over that span. From May 29 on, Walker has thrown 34.9 percent of his pitches while ahead in the count, the seventh-highest rate of 131 pitchers who’ve thrown at least 500 pitches over that span — and just ahead of eighth-place non-look-alike Kluber.

A performance change this stark seems to demand dramatic mechanical changes, but Walker hasn’t suddenly started mimicking another player’s delivery or leaping toward home plate. “I think he needed to lift his leg a little bit higher than he was,” Waits says. “It was a little stiff, I think you could say. I think he’s loosened up his delivery a little bit, and I think that’s really helped.” That difference is subtle, too small to stand out immediately on video when I compared his early and most recent starts. Waits emphasizes that Walker’s evolution isn’t solely physical: He’s also started to master “mental visualization — visualizing what that pitch is going to do and how you want it to go before you throw it.”

Walker, whose heater has averaged 95 mph this season and who feels “like [he] definitely has to take advantage of that,” confirms that his sudden strike-throwing is “more of a mind-set. Just being aggressive, just going right after them, not trying to nibble on the corners too much.” The location plots for his four-seam fastballs in each period tell the same story, with the second cloud sinking and contracting at the corners.

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Walker needs his four-seam fastball to succeed, because he’s still heavily reliant on his primary pitch: Since that magic May 29, no pitcher has thrown more four-seamers than Walker’s 514. But Walker has also refined his feel for the changeup (which is sometimes classified as a splitter) and tried to incorporate a third pitch, even though four-seamers and changeups still make up about 90 percent of his offerings. Most notably, Waits says, Walker has “changed his [curveball] grip, and tried to throw his curveball harder. It was a little too slow.” Specifically, Walker has started using the spike curve, a two-finger variant that Waits threw during his own big league career, and which a 2014 Baseball Prospectus study showed tends to be thrown harder than the traditional curve, with better outcomes and no cost in movement. Sure enough, Walker’s curve has added about 2 mph, on average, since April.

Those improvements to his secondary stuff have paid off in climbing curve and changeup/splitter whiff rates. “Eventually I’m going to have to start mixing more breaking balls in there … just to keep them off the fastball and changeup,” Walker says. Hitters haven’t forced him to yet, although more variety might help him reduce his home run rate, which remains higher than he’d like.

Walker has worked hardest on his command, taking a little off his fastball and changeup in order to come closer to his targets.

Command is difficult to measure, because we can’t say exactly where each pitch is supposed to end up. The best available approximation is COMMANDf/x, a Sportvision and MLB Advanced Media system that measures the distance between the catcher’s glove at the moment the pitch is released and the pitch’s final location. It’s not a perfect measure, since the catcher’s glove location doesn’t always correspond to the target, but large changes should show up over time. In fact, we do see some evidence of improvement when we split up Walker’s season. The differences are fractions of an inch, but as the cliché about baseball and small units of measurement reminds us, that’s enough to make the difference between a ball meeting or missing the barrel. In his first nine starts, Walker’s command was worse than the MLB average, in terms of the ball’s average distance from the glove in the horizontal (X) and vertical (Z) directions, and the combined magnitude of both; in his next seven,¹ it was above average.²

Walker’s emergence, only a little later than anticipated, gave Seattle the strong second starter it otherwise wouldn’t have had in the absence of Hisashi Iwakuma, who missed more than a month after straining a lat in late April. That’s especially rewarding for Waits, who’s been watching and working with Walker since the spring of 2011, when Waits was Seattle’s minor league pitching coordinator and Walker was about to enter the Midwest League. “I try not to visualize too much, when a guy’s in A-ball or Double-A, exactly what type of pitcher he’s going to be, especially when he’s young. But I will say I visualized him as a power pitcher who was going to come in and pitch off his fastball and throw in the middle-high 90s and challenge hitters. And that has been him. … He’s going to attack with what’s made him good right now. But I think also he’ll be quicker to adjust if he needs to.”

Neither Martinez — who’s pitched with a heavy heart following the death of close friend and teammate Oscar Taveras in October — nor Cardinals pitching coach Derek Lilliquist was available for comment about what Martinez has done differently this season, but his success seems to have a more obvious origin. Despite his big ERA drop, from 4.03 last season to 2.52 in 2015, Martinez’s peripherals haven’t markedly improved. But they haven’t markedly declined, either, which is unusual for a pitcher who’s transitioned from a relief role to the rotation. As expected, Martinez’s fastball velocity has dropped considerably since last season, as he’s paced himself in response to working exclusively as a starter since his second outing of the year.

For Martinez, the key to slightly raising his strikeout rate despite pitching at slower speeds — bucking the typical trend — has been a better changeup, a pitch he only occasionally broke out in the bullpen in its previous form. This year, Martinez’s use of the pitch has doubled, coming close to 20 percent.

Against left-handed hitters, Martinez’s changeup usage is approaching 30 percent — spiking to 41 percent with two strikes — which has helped him narrow his strikeout-rate split:

Fifty-four pitchers have thrown at least 200 changeups this season. Among that group, Martinez’s whiff/swing rate ranks third, behind Cole Hamels’s and Erasmo Ramirez’s. His ground ball rate ranks ninth, and his fouls/swing rate also places toward the top. Hitters who’ve swung at Martinez’s changeup have fouled it off or missed it completely roughly three-quarters of the time. And in that remaining quarter of swings — when Martinez’s opponents have actually managed to put the pitch in play — they’ve hit the ball on the ground two-thirds of the time.

In a post about the pitch last month, Jeff Sullivan included images of Martinez throwing the changeup in 2014 and 2015. Cropped and zoomed in, those pictures get a little Sasquatchy, but we can just make out the difference: Martinez’s middle finger runs across the seam in the 2014 image, and on the seam in 2015.

John Ronzani

Just as a different grip produced different results with Walker’s curve, Martinez’s new changeup grip has altered that pitch’s shape. As Sullivan observed, the changeup’s new movement is closer to that of Martinez’s sinker, whereas the old change moved more like his four-seamer. It seems pretty clear that this way works.

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Martinez’s ERA has outpaced his peripherals because he’s had better success with men on base and in scoring position, a quality he has in common with many of his teammates this season. Cardinals pitchers have a significantly higher strand rate than any other club: In other words, they’ve excelled at wriggling out of jams. That’s probably no more sustainable than their batters’ exploits at the plate in clutch situations in 2013, which they couldn’t replicate last season. Sustainable or not, though, it might help decide the NL Central race. According to Grantland contributor Ed Feng’s calculation of Cluster Luck — the degree to which a team has been helped or hurt by spacing out hits or stringing them together — Cardinals pitchers’ good timing has saved them more than 60 runs, almost double of second place Minnesota’s.

On the whole, the Cardinals haven’t been much better than average at limiting opponents on the basepaths,³ removing one potential explanation for their success at stranding runners. But this is an area where Martinez excels, placing fourth among pitchers in Baseball Prospectus’s Swipe Rate, a stat that assigns responsibility for base stealers’ results to the runner, the pitcher, and the catcher. (No one will be surprised to learn that Jon Lester ranks last.) Martinez holds runners by being unpredictable: He varies his time between pitches more than anyone else.

With the bases empty, Martinez takes 16.7 seconds, on average, to deliver the ball; with men on, he averages 24.5. Every pitcher delays longer when he has runners to worry about. But Martinez delays differently between each pitch. The standard deviation of his time between pitches — essentially, how closely his individual times are clustered around his personal average — is 7.99 seconds, higher than the other 96 arms who’ve thrown at least 500 pitches with men on base this season.⁴ Runners don’t know when to go because they don’t know when he’ll throw.

Martinez’s time trickery between pitches gives him, at most, a small edge. But he’s good enough now that we should care about his calling cards beyond the big fastball. At the start of this season, Martinez and Walker were still, for all intents and purposes, prospects: They’d lost their rookie eligibility, but we weren’t sure how good they could become. These days, they don’t deserve the label: For them, the present is exciting enough.

1. COMMANDf/x data from Walker’s most recent start wasn’t yet available.

2. The stats are similar for fastballs only, which Walker has worked on commanding the most.

3. According to Baseball Prospectus’s Opponent Baserunning Runs.

4. No. 97: Taijuan Walker, at 5.95 seconds.