Let me preface this by saying that I have not and will not give up on Lost until the series comes to an end. I've got too much invested in the story so far, and if the history of series television has taught us anything, it's that a show in a creative slump–and this show in particular–can always make a stunning rally and become stellar again.

That said, I have to confess that after the twin highs of Season Two's season finale and Season Three's season opener, Lost spent most of last fall disappointing me.

A sitcom or a procedural can weather a bum episode or two, where the characters veer off-model and the guiding premise slips a gear, but for a show with tight continuity like Lost–or Battlestar: Galactica, which had its own relatively minor misadventures last fall–a misstep can feel like a collapse. Imagine watching a movie or reading a book and suddenly, about halfway through, one of the major characters changes his or her whole philosophy, or a useless piece of backstory gets added that alters the nature of what the main story is about. That's what it felt like when Adama confessed to essentially baiting the Cylons into attacking Caprica on B:G*, and that's what it felt like nearly every week on Lost last fall, especially when Jack starting recanting his Hippocratic Oath left and right.

(*Aside: I'm still four episodes behind on Battlestar: Galactica, and I understand it ended strong last fall and started strong in the second half, so I'm still counting that episode–the only really bad one I've seen–as a blip, not a trend.)

Lost returns tonight, and I'm eager to see what I've heard is an excellent, back-on-track, all-is-forgiven kind of episode. But I'm going into this with clear eyes. A lot of damage was done over the six episodes that aired last fall, with characters being killed off not for dramatic purposes but because of behind-the-scenes trouble, and with new characters being introduced at the expense of the standbys.

As much as I love Michael Emerson's performance as Ben/Henry, his dominance of the show this year is indicative of what's gone wrong. Introduced as minor player, he proved so commanding that the writers changed his role, making him far more important, and effectively rendering a lot of what his character has said about himself completely moot (and kind of nonsensical). I still believe that Lost's brain trust can pull the character out of this dive, but I'm not convinced that they won't make other on-the-fly changes that push them further away from where they need to be. Every time some new concept is introduced–like Locke pushing buttons in the hatch–it can take a half-season or more for it to play out, since the story is operating on slow time. And though answers aren't always the reason to watch a show like Lost, a little forward momentum is a must.

But the biggest problem with Lost right now is what used to be its biggest strength: The flashback structure. Initially, the flashbacks were used to enrich the story, by telling us who these people were before they got to the island, and hint at how they might be connected. Now they only seem to be marking time, and only enriching the mythology. Fans spend more time scouring the flashbacks for clues than getting insights into why this particular piece of backstory matters, at least in terms of defining the characters. Put it this way: I have vivid memories of Kate's bank-robbing adventures and Locke's wheelchair-reveal and Hurley's lottery win. Yet I can barely remember a single thing I learned from the flashbacks this fall. (Was Kate a housewife? I forget what that was all about.)

I've heard that the creators have pulled together and have been talking about plotting out an endpoint for the series–Four seasons? Five?–which will enable them to know when dawdling is dawdling and when it's pausing for dramatic effect. And these are smart guys, with a gift for making the ordinary look profoundly creepy, so I'm counting on them to right this ship. Right now, though? They're … well, do I even have to say it?