C.E. Evans wrote:
It probably makes more sense to have TUC occur in 2291, going with the usual 300 year shift from the production date.
Then that shifts McCoy's arrival on the Enterprise
as CMO two years earlier to 2264, which means he originally served on the ship under Pike (McCoy said in Star Trek VI he had been the Enterprise
's CMO for 27 years, and VOY established Kirk's 5-year mission as taking place between 2265-2270).
What's to say he didn't serve under Pike for a little while? Or perhaps the Enterprise was in drydock for a 2-year refit between Pike and Kirk (2263-2265). So, McCoy came on board mid-way through the process.