If Shen is an LCS Problem

It's not just LCS, but coordinated play in general.

If the Shen is intelligent and coordinated with his team, he's far, far stronger than simply being those would normally justify due to his kit at any rank, from Bronze to the highest tiers of play.

We only tend to see this as an "LCS problem" though because coordination is far rarer at lower tiers.

And, even if he were just a high-tier problem, your idea leaves him broken at high-tier for most of the season, then just guts him for LCS, which isn't a viable fix either