R. Star wrote:
Leyton said something to the effect of "being more interested in ship design and engineering than command" of Sisko when trying to appeal to their past to talk Sisko into joining his coup. But yeah, Sisko saying he was one of the designers of the Defiant hints heavily at it too. Always figured Sisko was an engineering officer on the Okinawa before his promotion to Xo.
I think so, too. For all we know, he may even have been chief engineer before Leyton decided his future was in a red uniform rather than gold. Also, recall Sisko's words to Eddington after his promotion: "You could always transfer from Security to Command." It's sort of a retcon, but the way Brooks says the line suggests Sisko knows something about changing career paths as goals change.