Why Mike Yastrzemski and the Giants are sold on special soles: “If you slip, you lose”


It’s early July and Giants outfielder Mike Yastrzemski stands in the middle of a crowded clubhouse at Chase Field, unbalanced. His left foot is housed in an athletic shoe, but his right only wears a sock as he stands on the clubhouse mat. Addressing a visitor, it requests a corresponding configuration. “Take off your shoes,” suggests the 31-year-old.

It’s not some weird baseball superstition. On the ground in front of him is an insole that a few minutes ago resided in Yastrzemski’s right shoe, and the outfielder wants to demonstrate its advantages. This is no ordinary foam slice, he explains, but crucial equipment. He didn’t break into the big leagues until he was 28, yet he managed to carve out a career as a big league regular. And that bit of foam, which he started using before last season, is a big reason for that.

“There was a very, very important part,” Yastrzemski says, slipping the foam and then his foot into his shoe. “I think that really helped me a lot.”

These are Blumaka Konnect insoles and, if Yastrzemski and others with the Giants are to be believed, they could be the latest innovation in sports performance. Teams are already inundated with technologies that track force and plane of rotation and axis of rotation, and players are obsessed with their gloves, bats and cleats. And yet, no one has paid so much attention to what happens inside the shoe, where the foot can slip and slide. So far.

This “micro-slipping” is a problem Blumaka founder Stuart Jenkins claims to solve with his special insoles, which are covered in what he calls a “high-friction upper fabric.” The problem of slippage, he says, is one the footwear and athletic industries have long ignored, perhaps because it’s often imperceptible. But it happens, he says, and it’s ineffective. And in a sport that seeks efficiency, with analytically inclined front offices looking for any advantage, what happens inside the shoe is an unclaimed boundary.

This is why Yastrzemski is such a supporter. Two Decembers ago, he landed a pair of Blumaka insoles through a family connection, and he’s been using them ever since. He converted many others to the cause, including then-Giants batting coach Donnie Ecker – now the Rangers bench coach – as well as several teammates, including Tommy La Stella and Evan Longoria. Many never thought about how their feet moved inside their shoes until they tried Blumaka insoles. “I didn’t really notice how slippery they were,” La Stella says, “until I put them on and felt how anchored my foot was.” Most still use their original pairs.

For Jenkins, this solves two problems, one more pressing than the other. The main concern is durability. Eighty-five percent of every Blumaka insole is made from recycled high-performance foam waste, 100 million tons of which, according to Jenkins, are incinerated annually by major shoe brands. This was the problem he founded Blumaka to correct. But as he tackled this challenge, he thought of tackling another that had bothered him for decades: how a foot slips inside a shoe.

Durability is good for the planet, but stopping slippage is why Blumaka’s insoles gained such traction inside the Giants clubhouse. “When your foot slips even the slightest bit in your shoe, you won’t get your maximum power,” says Yastrzemski. Thus, from the waste foam comes the elimination of wasted strength. The extent of the impact this has is undetermined – Blumaka conducts biomechanical studies, although Yastrzemski has manipulated some of his own – but Jenkins says one thing is clear.

“If you slip,” he said, “you lose.”

Jenkins has been in the shoe business for 42 years, and the idea of ​​an affordable, durable slip-resistant insole has been on his mind for much of that time. “I saw someone trying to fix this problem in 1989, and I couldn’t get rid of it,” says Jenkins. At the time, “it just wasn’t feasible” or profitable. So he bided his time until the conditions were right.

In that sense, Blumaka has been both long in coming and short in market. Once Jenkins decided to tackle the waste foam problem – and the slip-in-shoe problem with it – he had a factory built in China that would be able to handle this type of material. From the moment he decided on a mold to work from, it took him 30 days to make his first prototype and another 60 days to perfect the sticky top layer of the soles. Soon after, the soles ended up in Yastrzemski’s shoes.

Mike Yastrzemski’s Konnect insoles have a non-slip upper coating to stabilize his feet during matches. (Courtesy of Blumaka)

Jenkins had a professional relationship with the outfielder’s father-in-law and wanted input from a professional athlete. So he delivered a pair to Yastrzemski in December 2020, then sat by the phone and waited. For months there was an agonizing silence – “It’s like sending your number to a beautiful girl you want to go out with but you hear nothing,” says Jenkins – but he thought pestering Yastrzemski for his opinion would only produce a false and hollow approval. .

Then, a week before spring training 2021, Yastrzemski requested another pair. This was followed by requests for five more, then another 10 – in a variety of sizes, to accommodate the different feet in the Giants clubhouse – until Jenkins’ limited supply ran out. Now the founder of Blumaka could expire. “If dogs eat dog food, it’s good dog food,” he said, and he kept running out of kibble.

One of the reasons was the comfort provided by the insoles. They are not very thick, which can make the wearer feel too big in their shoes, and yet they relieve pressure. “My feet usually hurt,” Longoria says. “I tried all the types of soles on the market. I’ve had custom orthotics made, tried all the over-the-counter things you can buy. This is by far the best result I have had with an insole. They also hold. Longoria is still on its original board, as are La Stella and Yastrzemski.

That durability and comfort are selling points, and Blumaka markets a basic insole that isn’t optimized for athletic performance. But athletes have been advised to support the arch for a long time. What sets Blumaka insoles apart for Yastrzemski and others is the grip they give the foot inside the shoe, which Blumaka achieves with a sticky top layer. (Think of the little rubberized dots on the bottom of baby socks, except they cover the entire surface.) Like Jenkins, Giants players have come to believe that to slip is to lose. The sport is about the effective application of force, and “you gradually dissipate the force the further you move through the cleat,” says La Stella. Indeed, Blumaka soles adhere so well that they often come out of a shoe with the foot of the wearer.

How much force is lost with normal soles? Blumaka is not yet ready to make any concrete statements. But Yastrzemski did his own testing in the team’s biomechanics lab at the spring training complex in San Francisco. “We have some things where we can look at our rotational acceleration” in his swing, the flyer says – rotational acceleration is measured in G-forces – and he noticed a 5-7g jump with the insoles compared to without. According to Blast MotionMLB’s average spin acceleration is 17g.

This matched what Yastrzemski had felt anecdotally.

“I could feel it in my swing,” he says. “I didn’t feel like I was moving as fast as I could (without the insoles). I did not feel stable in the ground. In a game where small perks equal big rewards, that’s definitely something I wanted to do.

One day last year, Jenkins’ phone rang. He picked it up to hear Ecker on the other end. “What are you doing?” Ecker asked, and the intensity of his voice put Jenkins on his back foot. “I think he’s like, ‘Hey, you’re bothering my team,'” Jenkins said. “I was as nervous as a long-tailed cat in a rocking chair factory.” Jenkins went into an explanation — “Donnie, I don’t really know what I’m doing, but I know sliding around in sports isn’t conducive to winning…” — to learn he was talking to his client the most interested.

Ecker has since bought, literally. In March he became one of Blumaka’s investors, and although he has yet to proselytize Blumaka’s benefits to his new club, he calls the company’s slip-resistant insoles a “100 million win. dollars” that will have applications far beyond the game of baseball. . “It’s going to transcend stick and ball sports,” Ecker says. “It’s going to go into physical therapy, it’s going to go into hiking and general health and movement.” He is also involved in the company’s biomechanical testing, which he says is producing encouraging early results.

“Some of the initial objective data tells us that in general, ground forces are increasing,” Ecker says. “We have a lot more stability with the knee and the hip when moving sideways.”

If there is going to be an insole revolution in baseball, it is only just beginning. “Sales are never where you want them to be,” says Jenkins, though he acknowledges that Blumaka hasn’t really tried to market his product. A YouTube demo of the insoles only has 27 views. Jenkins first wanted to put the soles in the shoes of top athletes like Yastrzemski to make sure they worked before ramping up production. (Jenkins says Yastrzemski received founders’ stock “as a thank you” for his feedback about a year ago. No other Giants player has a relationship with the company.) Insoles are available at purchase on Blumaka’s website, although Jenkins indicates a distribution agreement. with Drymax socks is currently in preparation.

If Blumaka’s reach can extend beyond the immediate circle of teammates who Yastrzemski can hand a pair of insoles to, it will give Jenkins a sense of accomplishment that baseball has long romanticized. It is the euphoria felt by the scout who discovers a transcendent talent toiling on a dusty and forgotten ground. It’s the exhilaration felt by the quant watching their team exploit a never-before-seen analytical tactic on the pitch. It’s the electrifying feeling of being first.

Jenkins already feels it.

“There are a lot of people who are paid dearly to fix these problems and they haven’t done it,” he says. “That’s pretty cool.”

(Top photo: Brandon Sloter/Icon Sportswire via Associated Press)


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