A tennis shoe usually dies in one of three ways.
The outsole goes bald. The toe blows. The cushioning turns into a board.
Bald in week three
Hard courts are sandpaper. Clay is dust and drag. Cheap rubber looks grippy on day one and slick by week three. We used real, high-density rubber meant for both surfaces. It has to survive the grind and still let you slide on clay.
The toe that rips first
You drag the toe on a slide. You plant and the mesh chews. Players report the toe is where pairs die first. Reinforcement that actually works is the difference between month one and month four.
Cushioning that goes flat
You can live with an ugly shoe. You cannot live with a dead midsole in the third set. Ours soaks up the baseline pounding and stays springy so you don't feel like you're running in mud.
If a prototype fails any of those three, it does not ship. That's the whole secret.