The Cardassians had individual ships that weren't a match for Maxwell's Phoenix or Picard's Enterprise, but as a state they were far more military-oriented than the Federation. If the Cardassians could out-number each Federation starship by 10-to-1 in an engagement, they could win every time. Eventually Maxwell would've been defeated, since eventually the Cardassians would've mustered a task force to destroy his ship.
Right. In video games (not cannon I know) Cardassians are presented as a race whose ships are designed for massed fleet engagements. They dont' work well on their own. They seemed to have been much more potent during Dominion War. It's also worth noting that Nebula and Galaxy class ships are not exactly the type of ship you'll find in every sector.