Starfleet would know from "BoBW" that any weapon only works against the Borg once. So building an invincible war machine would be wasted effort, and perhaps the Defiant always was: "threat becoming less urgent" would be an euphemism for "it failed utterly, totally and fundamentally, and the designers were idiots to begin with", the need for the chaste turn of phrase implicit in that it was one of the said idiots speaking...
On the other hand, a flexible platform would be great. Pulse phasers that can try out all sorts of weird frequency or flavor combos would work well, I suppose - well enough for Starfleet to be able to take this ship to battle several times. And the design certainly appears modular and malleable - you can see the seams! Perhaps the idea always was to change that bow section and those cheek modules when the previous anti-Borg systems within ceased to be effective.
As for "the start of a new battlefleet", that doesn't necessarily mean either that multiple ships of this type would have been built for swarm action, or even that the new fleet would feature any Defiant type ships. Rather, this would be the proof of the concept, the weirdo prototype, the first-ever submarine or jet, barely combatworthy but nevertheless a necessary first step.
But "the only warship in Starfleet" doesn't even deserve the scowl that Sisko gives to Kira for that cruel bit of mockery from the embittered freedom fighter who never got help from said Starfleet when her planet most needed it. Of course every Starfleet ship is a warship - even the runabouts can go toe to toe with enemy battlewagons, as seen. It's just that Starfleet seldom sees the need to skimp with other attributes, so their ships tend to be aces of all trades, while this proof of concept leaves many superfluous (and equally many vitally important) things ashore to hasten the prototyping process. The result is a fairly poor starship, one that Starfleet thinks appropriate for a suicide mission in "The Search", and one that severely underperforms, barely making warp 9 even with modifications to those poorly designed engines that threaten to do damage to the ship when used.
That Sisko makes some mean hooch out of that lemon is more the story of Sisko than of the ship that Sisko built. But being actually designed to fight the Borg must be an immense help in ST:FC, even if it is a potential handicap in other types of fight (surely the phasers must suffer from having their frequency unnecessarily rotated, say). Survivability is certainly a forte of the design!
Timo Saloniemi
