Widow mines do very little against Protoss since they can kill all the mines before getting into range. Hellbats protect the Tanks against Zealots much better then hellions do, but you still lose to mass Immortals.
Ghosts works but it is hard to get enough resources for both Mech, Ghosts and upgrades.
Is anyone successful with mech in TvP given equally skilled opponents? If so please describe in detail how you play the matchup.