RULE #1 should be an absolute "no-brainer" whether you are a football fan, fantasy nerd, or the producer/director of the presentation:
NEVER blackout or mask part of the presentation.
The blacked out portion not only eliminates part of your primary product, it also cannot relay any other information. Therefore, it serves absolutely no purpose whatsoever.
If you find yourself in the position that you've taken the historically unprecedented step of masking off part of your programming to address overscan - your graphics have evolved to the unacceptable point that they have "painted you into a corner" and it's time to start over with a different format.
There is no defensible position to justify violating this rule.