Game Theories: Epic Fails

I was having a late-night discussion with some designers at work about the nature of Succeeding and Failing in games. The question of the hour was this:

"In a narrative-driven or narrative-inflected game, what is a player's threshold for tolerating narrative failures with respect to gameplay."

To illustrate this, consider an exemplary assassination set-up in a typical Assassin's Creed game: You are given a target, and discover multiple approaches to reaching him. After choosing your path, you sneak up on the target and press the final "Attack" button. The assassination animation kicks in ... then cuts to one of the following cinematics:

1. You plunge your blade into the target's chest, killing him. [Success!]

2. You plunge your blade into the target's chest, but the target is wearing an iron vest a la the Man With No Name in "A Fistful of Dollars." Surprise! Your blade breaks. He has tricked you. After you wrestle, your target escapes. [Failure!]

3. You slam your fist down, but your target slips to one side at the last moment. The blade misses completely and slams into the ground. Your target rolls away and escapes. [Failure!]

Two of these scenarios end in narrative failure, one in success, and yet, in all three the gameplay loop is exactly the same -- the planning, approach, the execution of the attack. In all three cases, the player can be said to have "played the same game."