Nope because how the system is implemented - as seen in the API:
maPointEventManager service in module ngMangoServices
Provides an EventManager factory pointing to the point-value websocket endpoint at '/rest/v1/websocket/point-value'
All methods available to EventManager are available.
Used by <ma-get-point-value> directive.
So the only way to get around this is to write your own controller or component to provide just the data you want...
Fox