The cliché expression is: a shadow of [his, her, your] former self.

It's in the dictionary: enter link description here

• He is a shadow of his self. [not like he was at all before, either mentally or physically. Completely different]

By substituting ruin for shadow, a literary cliché is avoided.

The idea is that now the person is a ruin (something spoiled as in an old house) compared to the way they were before.

The cliché expression is: a shadow of [his, her, your] former self.

It's in the dictionary: Cambridge Dictionary definition

• He is a shadow of his self. [not like he was at all before, either mentally or physically. Completely different]

By substituting ruin for shadow, a literary cliché is avoided.

The idea is that now the person is a ruin (something spoiled as in an old house) compared to the way they were before.