I think the damage this card does is too much compared to its cost and rarity, especially in non-hidden games.
You discard a card from opponent's hand and replace it with a completely useless one and you also cause -1.5 stock to opponent approximately, with only 4 recruits and this card is a common. I don't mind the cards with replacing effect, but in my oppinion such cards with low cost should have a high impact on the player as well (for example
Mediator, which is an Uncommon 0-cost and is played at a risk).
Whereas this card is a common and I have seen people with 3-4 copies in hand at the same time and you can criple the enemy's strategy by just playing this at absolutely no cost to yourself. Discarding cards are way more dangerous than any damage cards, because they prevent the opponent from reacting or employing any strategy.
Now again, I don't mind the discarding cards, in fact they are a very nice touch in every deck. However, these cards should not be employed at will and costless by the opponent at any time. Most of them are pretty balanced. The only one I find a bit overpowered is this one.