My point is that the YE episode doesn't depict a radically different timeline. Perhaps it should have, but the producers couldn't afford to build all new sets and models and cast all new people in the episode. So we see a Picard commanding an Enterprise despite the alternate events of the timeline. If the events of the YE timeline lead to Picard et al. aboard the Big-E, how can we expect that everything else is radically different?
Sometimes small changes might generate wildly different results, but sometimes those small changes actually damp out. Given the rest of the episode depicts almost no differences between the timelines, I think it makes sense to think the Klingons of YE are not much different than the ones in the prime timeline. Therefore YE suggests the KDF could whip Starfleet in a prolonged war.