Wait, why CAN'T Bob be a champion?
Just think: While repairing the turrets after a particularly disastrous match on Summoner's Rift (Kog's goo takes FOREVER to scrub off of stone!) DISASTER STRIKES! Through some strange accident, poor Bob all of a sudden finds that he can conjure similar magical bursts to what the turrets do.
Unfortunately, this causes him to resonate with the sensitive magical nature of the turrets, and poor Bob loses his position at the League due to his not being able to work with the sensitive stone and enchants anymore without causing magical feedback.
Poor Bob is a skilled enchanter, engineer, and stonemason. Defeated, he goes home to his wife and three children the day he's sacked. His wife leaves him. His children, while they find his new abilities neat, can't stand the fact that their "ordinary" dad now has magical powers and won't do anything with them
Bob loses it. Determined to prove himself to his family and friends, he crafts himself a set of enchanted armor that is a whimsical mix of technological and magical elements. He shows up at the league wanting to prove that even the little people can make a name of themselves.
Morello, IronStylus, would you turn that poor soul away at the gates? That turret repair guy has a story too.