Is Joy really an S-tier jungler? Seems pretty weak to me

Just reached mythical glory a few days ago, and I've noticed that every match that has a joy will pretty much be a lost. She's always ranked S-tier in the tier lists, but somehow I feel she's like a B-level jungler at best. One stun and it's over for her. Probably only seen 1 or 2 games where a Joy has won (out of the 20-30 matches I've gone against/with her). But even then it wasn't the Joy who carried, but rather they had a late game Layla, Cecillion, Sun, Argus, etc.

Perhaps she's only good in a 5-man team? Even when up against a trio I've still seen her being hard countered every single time.