Where will this new system be implemented?
How will it stay objective?
Will you go back and review all previous mods or only new mods?
If I was a reviewer my views would vary greatly from others. I only play the sp game so any mp only mod would unfortunetly receive a low score for me. It wouldn't be fair.
If someone only played mp, as is mostly the case, they would be harsher for mods that related to the sp portion of the game. Not fair either.
Your system is too subjective.