Re: Starfleet Command Insignia
Maybe there was no captain of the Lexington? Perhaps she had been or was being readied for some type of refit and pulled for the M-5 experiment because she wasn't being used elsewhere? Perhaps Wesley was it's former captain and was recently promoted then pulled some strings to get back into the captain's chair for the M-5 trials?
I find this extremely hard to believe. "Starship captain" is one of the most wanted jobs in the 23rd Century (driving people insane because they don't get it). And captains like Commodore Decker or Commodore Wesley seem to be the "right stuff", especially in contrast to the bureaucratic flag officers we've seen elsewhere in TOS.
"The first duty of every Starfleet officer is to the truth, whether it's scientific truth or historical truth or personal truth! It is the guiding principle on which Starfleet is based! Jean-Luc Picard