Oh, for fun, among players with 300 PAs, the Nats have had 3 of the bottom 6 by fWAR: Rosario, worst at -1.8, Meneses, 3rd worst at -0.9, and Ruiz, 6th worst, at -0.7.
Technically, I think it is unfair to call them AAAA players. AAAA players are supposed to be available for MLB minimum, capable of being plugged in as a replacement immediately, and perform at 0 WAR. Keibert is below replacement and < AAAA.
Somehow, we only have the 3rd worst catching in MLB. Worst 2 are the Chicago teams.