varus backbround and gameplay

so while I was reading varus background, this part got my attention.

"""A hook-spear swung at Varus. He dived to the side, rising to his feet and sending a pair of crimson shafts through his attacker’s chest. Varus sprinted, leapt and dashed through the ruins, blazing shafts of light eviscerating his targets with absolute precision. In seconds it was over. Sixteen dead, and he hadn’t even broken sweat"""

AND to be specific

"""Varus sprinted, leapt and dashed through the ruins .........and he hadn’t even broken sweat""

AND in the background they mention how strong and fast is his body.

yet in game he feels like a turtle :p how does that design fit the background ? lol