I've mentioned somewhere that Dungeon is probably the most unpredictable Castle. With a bit of luck, they can even dominate against Necropolis and Conflux, which are traditionally considered the strongest factions... but if luck isn't on your side, they can easily lose, and even the player's skills won't help – (((
Of course, anyone can be unlucky, but some handle it better than others. Dungeon is more likely to be on the losing side. -)
P.S. And why are Scorpions considered weak units? I don't remember where, but I saw some not-so-positive reviews about them... In my opinion, they fit perfectly into the Dungeon's tactics – they're fast, they fly, and while they're not great as a strike force against Nagas or Knights, they're excellent at blocking and holding back Cyclops or even Titans for a while! I remember my 28 Scorpions fighting 9 Titans in melee combat for 3 turns... they fell, of course, but they also did a good job damaging the Titans and forced the enemy to divert their attention...
I think it's time to rehabilitate the Scorpions and admit: Dungeon doesn't have any weak fighters (in terms of attack, defense, and speed)... except for Trolls. I don't play as Shakti