mere shadow of one's former self; ruin of what one once was
Describes a person or thing that has fallen into a wretched state, a mere remnant of its former glory. Often used with a negative or pitiful connotation.
He became addicted to alcohol and ended up a mere shadow of his former self.
かつての名門チームも、今では成れの果てだ。
The once-famous team is now just a ruin of what it used to be.