Thanks for the linked article. However, I don't really see how that change makes any sense at all.
Did you play titans map? The deep one sits under a mark of the keeper. And he teleports units close to him making it impossible to swap him out without clearing the mark of the keeper in the first place. Furthermore, to my opinion, the deep one is not that useful, as it's hard to keep him alive given shadows only support spell at t1 is the one reducing damage by 50%. You charge in one base and probably lose the deep one afterwards.
Rageflame is a good card, but once i realized that i can't swap the unit to anything useful, I was discouraged to check the ability at all, as I considered rageflame clearly t3. It's completely unexpected that you can change it to it.
Furthermore, this change made parasite swarm one of the most useless cards in pve if you don't have all 3 upgrades (I've found out about it the hard way).
For me, it looks like the goal was to make nightguard reasonable weaker and I do agree that the card was quite powerful in the first place. However, aren't there always powerful t1 cards?
Nature: Mana Wing / MoK
There is no real replacement for these 2 cards in any other faction.
In terms of pve-survivability at t1, nature got cc and heal, fire got suppression and damage spells, frost got cc and wintertide while shadow got nothing? Unless you count soulspicer as a viable option.