WHEN DID THE TRAIN GO OFF THE RAILS?

For those who were angered, confused, disappointed, betrayed or dumbfounded by the End, there is something for you to consider: when did the LOST train go off the rails?

One has to take personal theories out of the discussion. For a few, LOST did not End like they "thought it would." Adding insult to injury, those who adorned the End hedge the conclusion without all the answers as being the TPTB's present to the audience to make up their own final theories. But in rebuttal, it is the job of the author to put together a satisfying and/or clear ending to the author's story.

So when did the LOST creators get lost?

From a practical perspective, it was probably during the end of Season 1, when ABC renewed the series. From that point, the creators had to create more episodes and create buzzworthy filler to the end game.

From a plot line perspective, it may have been the need to continually add new characters to keep the mystery engines going full throttle. The addition of the Tail Section survivors had little lasting impact on the final story arcs. What about Nikki and Paulo? Yeesh. Dharma and the Others, the time travelers, the Temple, Ajira survivors - - - more red shirts than red meat for the story.

From a character perspective (it was all about the characters we have been constantly been lectured since the End), what character event put the story arc(s) down the rabbit hole?

The death of Eko?
The disappearance of Claire?
The whole ghost Christian thing with Jack?
Michael and Walt leaving the island by betraying the other survivors?
Faraday's death and the end of sci-fi explanations?
Juliet's death and the end of time travel to the void of the after life?