A pivotal week has arrived for a number of Alabama high school football teams. With one-third or more of their schedules already completed, they’re now looking to build momentum down the stretch ahead of playoffs in November. That begins this week with a number of key matchups on slate, including four top-25 tilts that could have major impacts on seeding down the road. Below are the key games to watch this week in Alabama: The On3 Massey Ratings, officially used during the BCS era, is a model that ranks sports teams by analyzing game outcomes, strength of schedule and margin of victory. Accord…