I got this from TVTropes.

Tidus’ fighting style is improvised but awesome and practical. Most of his moves are based on typical blitzball moves but wielding a sword.

But Tidus is rubbish at offense in Blitzball. His strength lies entirely in shooting (with his feet, which he does not use to wield his sword).

The last part was a counter. Of course, he has to use a sword. That’s the whole point. Notice how he moves on the field during his OverDrives. Especially Slice and Dice. Slice and Dice is similar to suicide drills.

Even though Tidus’ class is like that of a Warrior:

His path on the Sphere Grid leads towards high Agility, Evasion, and Accuracy growth

Agility, Evasion, and Accuracy seem like skills a sports player like a blitzballer would naturally develop. Whereas Kimahri and Auron are both warrior and monk with a focus on strength. Tidus has a focus on agility.

Why doesn’t Wakka do what Tidus can do? Because he’s fat. Can’t you tell?