They seemed evenly matched in the 23rd Century. Neither Kirk nor Kor seemed especially fearful of the other.
True.
Deep Space Nine had a third of the Klingon fleet engaged in the Cardassian invasion and yet the station repelled the attack. Both Klingons and Federation had reinforcements on the way.
The war is specifically referred to in dialogue as not going well for the Federation.
I don't remember the specifics of Discovery very well but the Feds had a bomb to destroy Kronos and a mycelial super ship that could see through cloaks and be anywhere in the galaxy in the twirl of a saucer.
Which did not stop the Klingon fleet from being visibly on Earth’s doorstep at the end.
For me "Yesterday's Enterprise" is the most damning. But who knows where the future might have gone? Maybe the Klingons lost as many or more of their ships to Starfleet as well but were used to sacrificing a lot – Russia in WWII? Plus in that timeline the Federation flagship was lost at Narendra III. Could it, 22 years ago, have been the ship that turned the tide in battle against the Klingons, butterfly-effecting a different future?
Anything
might have happened, up to and including Q arbitrarily dropping by and changing the outcome; but based on Picard’s dialogue in the episode, the Federation was losing.
...I dunno, but I'm glad it wasn't an easy victory for the Federation. The Klingons haven't been scary for a long time. (Points to T'Kuvma & Co. eating Georgiou's body.)
I think there’s always been a tendency in Trek fandom (other than Klingon fandom, I guess) to assume that of course the Klingons aren’t
really a threat to Starfleet, if it comes down to a straight-up fight. My point in these posts has been to suggest that in fact, in-universe, that was never the case, and the Klingons were
always scary, even when they sometimes seemed like saps to us viewers.
Is that science or mysticism? Time crystals (forehead smacking Marvel stuff) basically work by being touched. By man or squirrel. That's it. No science to it.
Oh, it’s complete made-up bullshit, as far as real-world science is concerned (“Time crystals”
are a thing, but
they don’t do that), but it doesn’t matter: In-universe, it works, so it’s real, so it counts.