When I say flanking tank, it doesn't mean it has to maneuver a lot ; let's say you play with RISE Pattons or AMX-30B Valorisés as the most outward units. Then you use your M1A1s more or less in the middle but with a very good lateral separation, so that if the enemy dares to fight you, you'll have a very fair chance to get side shots with the M1A1s, even more if the enemy engages your flanking tanks. The only units that can shoot from the center and hit the front armor shall be the ATGMs, and if it's possible, you shall even move them to get side shots.
Even though the M1A1 is slow with 50 km/h, the enemy can't move very fast either ; only the T-80s are really fast, while the other PACT tanks are either ineffective while shooting on the move to stay far enough from the M1A1s, or if they want to stand still to fight your RISE Pattons or AMX-30B Valorisés, they'll expose themselves to your 120mm DU shells of justice !
The M1A1 is worthless if you fight the T-80s head-on without moving ; if you force the T-80s to move, they already lose a lot of their effectiveness. Your job is to manage to get the most of your force to engage the T-80s without losing too much to their flank guards.