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.