The Star Trek franchise has long been a serial abuser of the Time Travel plot device. That being said, Deep Space Nine has probably used it most effectively, either for social commentary (as in Past Tense) or emotional impact (The Visitor and Children of Time). One senses an attempt to do the latter here, but the episode is a mess, from the conceptual level through to the execution, and even O'Brien's use of an Irish curse word can't save this one.
The idea is high-concept: Molly O'Brien falls through a time portal and is later retrieved, but she is retrieved from an alternate timeline where she has lived away from her family for 10 years. She has the expected trouble re-adjusting to DS9. If you have seen literally any movie about a "savage" coming to civilization, you will be bored with this one. It has little to recommend it. One could see the makings of a good black comedy here: O'Brien keeps trying to pull his daughter back, and keeps getting different-aged Mollys back. Instead, it's melodramatic and overwrought, and it resorts to the cheap narrative tack of the "reset button" to make the episode self-contained. The reset button is a tactic better suited to TNG or Voyager, which catered to the three-times-a-season viewer, but with Deep Space Nine, serialization was built into the show deliberately.
Ultimately, this feels like a warmed-over TNG reject episode, which is unfortunate, since having a post-pubescent "savage" Molly might have been an interesting arc. It certainly would have been a bold one, and DS9 was usually unafraid of taking chances. Instead, the episode not only misses that opportunity, but also the opportunity to make effective use of time travel.