"Playing for...huh?! You're still in high school?!"

No waaaaaaayyyy. Although, maybe if Sena squints a bit, maybe your face is a little more rounded and less adult like...?

...

Nah.

Actually, no wait, what you're talking about?!

"Wha-? My legs are just fine, thank you! I mighta pushed them to my limits back there, but they never broke or anything!!!"

He's got the mental image of a younger version of him with his legs broken like glass, scattered in pieces across the field. Agon can probably almost see the thoughts dancing around in his head in confusion.