And again, position in the galaxy, warp speed being traveled, etc all affected the Stardates:
"They marked off sections on a pictorial depiction of the known universe and extrapolated how much earth time would elapse when traveling between given points, taking into account that the Enterprise's warp engines would be violating Einstein's theory that nothing could exceed the speed of light. They concluded that the 'time continuum' would therefore vary from place to place, and that earth time may actually be lost in travel. 'So the stardate on Earth would be one thing, but the stardate on Alpha Centauri would be different,' Peeples says. 'We thought this was hilarious, because everyone would say, "How come this date is before that date when this show is after that show?" The answer was because you were in a different sector of the universe."
-Joel Engel, explaining Stardates based on interview with Samuel Peeples, who wrote "Where No Man Has Gone Before" episode and brainstormed the Stardate system with Roddenberry.
There's no real rhyme or reason to it. They're completely random, and this quote, as well as quotes from Roddenberry himself who says same (that position in galaxy and warp speed affected the Stardates so they're not linear or in a progressive order).
From TOS series bible:
"Stardates are a mathematical formula which varies depending on location in the galaxy, velocity of travel, and other factors, can vary widely from episode to episode."
So, again, don't make mistake of taking Stardates as definitive markers of a chronology for the show.
The production order is the generally accepted chronology for that reason.
It's also why viewing the 1000 dates as first year, 5000 dates as fifth year is also likely an invalid assumption.
"They marked off sections on a pictorial depiction of the known universe and extrapolated how much earth time would elapse when traveling between given points, taking into account that the Enterprise's warp engines would be violating Einstein's theory that nothing could exceed the speed of light. They concluded that the 'time continuum' would therefore vary from place to place, and that earth time may actually be lost in travel. 'So the stardate on Earth would be one thing, but the stardate on Alpha Centauri would be different,' Peeples says. 'We thought this was hilarious, because everyone would say, "How come this date is before that date when this show is after that show?" The answer was because you were in a different sector of the universe."
-Joel Engel, explaining Stardates based on interview with Samuel Peeples, who wrote "Where No Man Has Gone Before" episode and brainstormed the Stardate system with Roddenberry.
There's no real rhyme or reason to it. They're completely random, and this quote, as well as quotes from Roddenberry himself who says same (that position in galaxy and warp speed affected the Stardates so they're not linear or in a progressive order).
From TOS series bible:
"Stardates are a mathematical formula which varies depending on location in the galaxy, velocity of travel, and other factors, can vary widely from episode to episode."
So, again, don't make mistake of taking Stardates as definitive markers of a chronology for the show.
The production order is the generally accepted chronology for that reason.
It's also why viewing the 1000 dates as first year, 5000 dates as fifth year is also likely an invalid assumption.