Most underpowered cards suffer more from lack of purpose rather than not making enough points to provision cost ratio.

A problem I've seen for a long time is that, tweaking power or provison, although could and it have made some unplayed cards playeable (ie. Maxi, Drowner) this kind of changes don't suffice with a lot of cards, because those cards being unplayeable doesn't rely on the points they generate per se, but the purpose that that cards fulfills in a deck or gameplan, some examples are.

• Toussaint Knight-Errant: Although it is a very easy 7 for 4, it achieves almost nothing in any deck, NG doesn't have many cards that could deal small instances of damage to finish a 2 power enemy unit, it is not proactive nor helps any other conventional NG gameplan
• Recruit: NG can't take advantages of boost, not like NR at least, and a 6 for 4 that's not proactive and doesn't protect any engine is plain bad, even if it was a 4 that boost by 3, it wouldn't matter
• Menagerie Keeper: The card that made me realize this problem, in paper, is a very accessible 7 for 4 in a full or medium full tactic deck, why is not played? Simple, it achieves nothing, tactic decks are control based, you deal wiht units killing them off directly either with Joust or Assassination, why would you play a card that can only kill 2 power units thus losing its bleeding value or kill 4 power units and give your opponent 2 turns to answer the bleeding? It has no purpose in Tactic decks, is onlu playable in those decks because its condition makes you to have a tactic in hand, but if you need soldiers, aristocrats or agents in hand, you wouldn't play this card in those decks because its ability is very plain, 2 damage and 2 bleeding achieve nothing

The biggest problem with weak cards is that either their ability is tied to a condition but that ability itself is very general or even anti synergestic with the condition or lack a purpose, a great example of a good card is Little Havfrue, in paper it is just an Elder Bear that trades 4 health for 2 turns of rain, but in practice is so much better than that, it offers proactivity to a faction that often lacks it, it offers a good amount of instant points and the possibility to spawn rain wich helps with Bloodthirst, damage pings for Greatswords and Onslaught passive.

So, what do you think?