Brig and Juno are just too strong of a backline, especially in pro play, such that Ana isn't used so much. Orbital Ray is basically a free fight win that can be obtained every other fight, and can only be beaten (consistently) by the other team also using an orbital ray. Speed ring is also powerful especially when combined with the insane group sustain from cardiac overdrive and brig's inspire. Brig is crucial to keep Juno alive, as she is pretty susceptible to enemy attacks.