Being a M1 crewman for 7 years, i'll add this...
The M1 is a very good tank. However, the reason (IMHO) US Armor units have such a drastically slanted kill ratio in RL and in the game is because of the people IN the tank, not the tank itself.
From my perspective and recollection, I can only imagine just how motivated and squared away the crews who are actually in combat are. We train and train and shoot gunnery, then train some more. SIMNET/UCOFT/"New SIMNET thing" (can't recall what it is named) hones the skills very well. Now, put these highly motivated and trained killers in a situation where they get to shoot live bullets and real bad guys....
Frankly, I pity the bad guys who have to face them. LOL I mean, I know how geeked I got to just go shoot practice bullets at plywood during gunnery. Perhaps this is a hard thing to explain to people who have never been in a armor unit?
Anyhoo, it is not JUST how good the tank is... It is the "ephing" amazing crews IN those tanks that make the real difference. IMHO. Like somebodyelse said... Staying organized and the pointy end at the bad guys....