I can say with near certainty that this is Iwakuma Hisashi's form. As an aside, the only reference I could find to the 二段モーション in English was on an English-language Japanese Baseball forum referring to it as the "Stop Motion Wind Up" here.

It took too long for Japan to anthropomorph horses into idols. That made wonder how long it would take for their other national sport to be involved. We are this close to "moe" historical baseball players now: almost there.

rom_collector said:

It took too long for Japan to anthropomorph horses into idols. That made wonder how long it would take for their other national sport to be involved. We are this close to "moe" historical baseball players now: almost there.

Nah. There was captain tsubasa and the Moe version but uses unique character with the usual overseas players too. Also speaking of basketball ryo-kyu-bu exist.