Looked at the stats and I think I know why it sucks. The US Mortars have the highest scatter of any mortar-type unit in the game. Their accuracy is even worse than the Soviet 120mm Mortar, and the Pack Howitzer is about the second worst.
Another problem is the short range, the Pack Howitzer only has the range of a normal Mortar (80) while the ISG and 120mm have 100 Range. The MHT has a range of 60, 20 meters less than a normal mortar.
Best solution would be to tighten the spread a little and increase the range of each by 20 to properly match their counterparts.
