Umbran said:
shrug* Another mainstay of fiction - wits, guile, and tenacity win out over brute strength.
Kirk won out against alien forces with vast powers - the Squire of Gothos, an Olypian god, the Doomsday Weapon.
Kirk only defeated the doomsday weapon because another ship captain sacrificed his life in an assist. The Squire of Gothos was overcome by other powerful alien beings. The Olympian gods were overcome by discovering their secret, and matching their power.
Picard stood up against the omnipotent Q time and again, as well as his crew beign the first folk to face down the borg multiple times. Time travelling borg, even, if you count movies.
They encountered the borg five times in TNG (if you count the movie). I'd hardly call their encounters a ringing success.
1. When Q tossed them out in space to the original borg cube, the borg pretty much cleaned the Enterprise's clock,
and it was only the subsequent intervention of Q that saved them.
2. When the borg cube showed up to attack earth, it was only the fortuituous circumstance that Picard gave away a borg weakeness that allowed humanity to escape. The Federation fleet was annhilated in the process.
3. A
lone borg was captured by the Enterprise, and although they caused him to develop individuality, they were still so convinced of the danger of the borg that they made sure to return him to the borg.
4. Lor led the disaffected borg against the Enterprise, and despite the fact that they were dealing with a disorganized rabble of a borg group, the heroes were only able to survive by the timely intervention of Hue.
5. A tiny force of borg went backwards in time and despite the fact that the borg ship was destroyed, they killed or assimilated so many crewmembers that they took over the ship. Only the treachery of Data allowed the borg to be defeated, and only after the crew paid a hefty price.
Sisko held off the Founders and the Pah Wraiths...
I stopped watching the mind numbing boredom that was Deep Space Nine long before these events took place, so I have no comment on them.
In all the other series, the characters do the same basic thing. They generally don't get by because they are more powerful, or even on equal footing. They win (and are considered heros) because they beat the odds.
This goes on to other genre shows - on B5, a small human crew is responsible for beating the Shadows (and the Vorlons, actually), the Psi Corps, and their own government - all superior forces. They do it not by being strong, but by being bright, and in the right 
No, the small human crew is able to get support from one of the military superpowers in the universe (the Minbari), and virtually every nonaligned world in the setting. They form the "largest fleet in history". I'd hardly call that beating their enemy from an inferior position.
Earth is taken on with Minbari help, Psi Corps isn't an enemy of the Babylon 5 characters until Season 5, Bester was actually allied with them through Season 4, and by the time Season 5 rolls around, Sheridan is the ISA President, hardly dealing from a position of weakness.
In many cases, there is plausible help for the outmatched, or the villans had agendas that precluded using their full force on the heroes (for example, Babaylon 5, where the Vorlons and Shadows wanted an ideological victory, not a physical one) which is what makes the stories work. There was very little justification in Voyager for that, which is what made the storylines implausible.
