Starting the game with a 14 power +1 in hand: good
Not having control of what cards are played and where: bad
The solution is to get Agatha out of your hand as fast as possible and minimize the risk while she is in control.
This deck is a gamble; you need to know when to check, when to raise, and when to fold. Sometimes the discard plan doesn't play out, sometimes you can salvage the game with Infinaut or a raw Agatha play, sometimes just the big bodies are enough to squeek one through, and sometimes your own deck bodies you harder than any opponent can. Don't be afraid to play a game out even if Agatha is making really bad decisions though, wait until you are cornered by an opponents snap or down to the last turn at a disadvantage.
I've hit Vibranium last season with this deck (or similar builds), and despite being in a higher collection level queue I'm climbing back up. Don't sleep on Harkness, just because sometimes the deck will feel like the worst thing ever, it can also beat top tier decks out of nowhere. Be smart with snaps/retreats and this archetype has what it takes.