which makes it very easy to be a Monday morning QB.
To really give a substantive answer you would need to be watching the game from an all 22 perspective, meaning you need to be at the stadium sitting up high close to the middle of the field.
Understand the scheme in relation to talent and offensive tendencies.
Know how to adjust within the restrictions of your installed and practiced playbook
And finally be able to relay these adjustments in a clear and concise manner in the 8-10 minutes you have with the defense at halftime, to minimize confusion and compound mistakes.
In other words, beyond generic things like blitz more, play more man to man and put in (insert random backup name here) you are not going to get anything of substance that is feasible from 98% of the board.
They are just fans that want to win, so they will just spout random buzzwords and call for something opposite of what the coaching staff did, with no understanding of the moving parts.