It was gutted in this patch:
M4A3 Sherman
The Sherman's HE shells have been adjusted to be more reliable at dealing damage, but also less capable at wiping out squads.
Projectile now bypasses terrain/landscape.
HE shell AOE distance from 0.75/1.5/2.25 to 0.5/1.25/2.25
HE far AOE damage from 0.05 to 0.01
The first sentence was utter rubbish. They decreased the AOE to 20% of what it was, which didn't make it more reliable. It never had a significant problem with colliding with terrain.
I wasn't playing back then yet, but nowadays sherman has the best AOE, in my opinion, with HE shells out of medium tanks. Guessing it used to be quite a beast.