By TOM SHANAHAN Navy travels to Air Force Saturday for the first round of the Commander-in-Chief’s Trophy rivalry. It’s a meeting unlike any other in the series, although that goes without saying in the COVID-19 pandemic-impacted season. Unusual factors to weigh include Air Force playing its season opener, while Navy (1-1) is entering its third game. When the Mountain West Conference postponed its season to the spring, it made an exception to allow Air Force to play its…