They won beacuse Sisko was the "emisery".
They didn't get a piric victory becuse Odo was a friend.
Although I haven't seen the episode in a long time, but in
What You Leave Behind I'm pretty certain it was due to the plague that the Dominion backed off. IIRC, the Emissary took out one of the Dominion's fleets, but that was hardly the act that won the war.
They are great "diplomats".
Uh, how is that at all related to the points I made? I point out that the Federation had to ally with other powers or trick them into fighting the Dominion, to which you reply that they are good diplomats?
Gsc formed the back bone of the fleet that took back DS9 and that attacked chintoka. They performed well. Are good ships.
They could still be a lot better. If Starfleet had had a GCS-sized ship devoted purely for combat around, their losses wouldn't have been nearly as high.
As for the Galaxy class being a good design; you
have seen TNG, right? They're by far the most accident prone and flawed ships in sci-fi history.
"You've all been selected for this mission because you each have a special skill. Professor Hawking, John Leslie, Phil Neville, the Wu-Tang Clan, Usher, the Sugar Puffs Monster and Daniel Day-Lewis! Welcome to Operation MindFuck!"