[Merkle923]

Your surmise on the A's unis in Spring Training 1972 is correct - new caps, old shirts and pants. All Topps' images from the A's that year look

Not an uncommon thing, especially in the '60s and '70s. The Braves, for instance, wore their 1971 traditional gray uniforms but their new multi-colored small "a" cap in Spring Training 1972.