Sometimes a movie is not sunk by the script, the direction, or even a bad ending. It goes off the rails because one actor pulls every scene in the wrong direction, draining tension, killing the mood, or making the whole thing feel ridiculous whenever they appear.
People can forgive a lot when a film has style, ambition, or a few great moments worth holding onto. What they do not forget is the face attached to the collapse, the performance everyone blames when a promising movie turns into an uncomfortable, frustrating, or unintentionally funny disaster.