It's been my experience that players know what's going on in front of them, but rarely going backward. Which is to say Safeties should know fronts. Basically, if the call has an impact on your responsibility, I feel like you should know what your teammates are doing. I realize that's not always the case. I played with two corners who I reminded almost every play what their responsibilities were. Ironically, we played a ton of Cover 3 (and pattern matched at the ****** HS level!) and some Cover 4.