Size doesn't matter
Take the size of that Executor...then compare it to the Krenim Imperium Temporal Incursion ship (hint, it's to the left of the Borg Cubes).
1550 meters vs 17484 meters....hardly a match, you'd think.
But...when that same tiny Krenim ship goes back in time and wipes out the founding planet of the Galactic Empire before they'd even reached space flight....then you realise just how much size matters