Guess it still annoys me that Harry Kim is the Security Chief now Operations....and I think, "When the hell did he ever express interest, let alone get training in it?" And not only he got ship security training but leads landing parties firefights.
Hell, even in the Navy, the Navy officer that runs ship security does not have the same skill set as a naval officer that "takes the beachhead" And if there is someone who does possess both skill sets, didnt just transfer into that position after serving numerous years in another area of expertise.
Yes, yes, it probably is a plot device, but I just wonder if anyone saw the same thing. I guess the argument that Checkov went from Navigation to Security, but when he was navigator he wasn't the Chief Navigator (unless an Ensign holds that spot). Even Sulu, wasn't he in Botany sciences for a while before he became the Helmsman. I don't think Sulu was the chief botanist on the ship.
No, Sulu was the astrophysicist in the second pilot, then moved to the helm. Botany was one of his many hobbies.
There's a lot of cross-training in Starfleet, and it seems particularly common for people to move into security from other jobs -- Chekov from navigation (after a stint in science and, according to the novel continuity, a previous stint in engineering), Worf from bridge watch officer, even Nog briefly serving as DS9's security chief before Ro took over the job (though that wasn't technically a Starfleet post at the time).
But we've seen other transfers too -- aside from Sulu and Chekov, Geordi moved from helm to engineering, Worf from security to strategic operations, O'Brien from tactical to engineering (with a stint at conn in the TNG pilot), Ezri from counseling to command-track (in the novels), etc. Plus all the background players in TOS who moved from job to job as the script demanded, like Leslie and De Salle and Martine.
I figure the rationale is that Starfleet training is broad enough that everyone's given a grounding in a variety of disciplines, on the principle that if you're on a ship way out in the unknown and you lose some of your crew, you need others who are qualified to take their place (as we saw in Voyager
, with Tom initially doubling up on nursing duty, Harry essentially doing the science officer's job for seven years, etc.).
I do agree, though, that they should've had distinct characters as the DS9 ops crew and the Defiant
crew. It's not as if DS9 had any reluctance to populate the station with a large group of supporting characters, so why not add a dedicated Defiant