One issue with the 76mm Sherman design in particular is that it only works against medium spam, which in turn is only viable in 1v1 and 2v2. All other modes will see Panther, Brummbar and heavies, which the 76mm even on HVAP is not great against. Otherwise you will need a Jackson anyway, so there is no need for a 76mm Sherman.
Next, to get the most out of it against mediums, it should be on HVAP consistently. This leaves a big gap in the AI department. The 75mm Sherman is a beast against infantry, it has the HE shell for a reason: USF usually need it for the mid/late game. The 76mm does not have this option. It is "okay" at best against infantry, but for that you have to use it on the normal shell, which is not that efficient against mediums.
While the increased AT makes up for it on paper, it might not make up for it in the context of USF.
The rest is a commander issue:
Dodge truck and M3 are good in 1v1 with diminishing returns in larger modes.
Cav Rifles - not sure, but you'd usually want to focus on indirect AI in larger modes rather than CQC units.
Combined arms - Good in all modes
Mortar half track - Good primarily in 2v2 and up.
Overall this focusses the commander pretty much on 1v1 and a bit of 2v2. It is very uninteresting in all other modes. It could overall need some buffs, it is barely used at all.
From 2vs2 perspective:
- WC51 is only effective vs OKW early game, You don't have enough room vs Ostheer to use it effectively. And then since you need 45 munitions to get the .50 the windows of effectiveness is extremly short unlike the UC.
- M3 is useless in majority of cases, better having 2 ambulances, one in your base, one on the frontline for the same cost than 1 ambulance + 1 m3. Unless you want to try hard with m3/zook.
- Mortar HT is a joke costing too much fuel or/and munition if you want to use the WP round. For what it provides better investing in a regular mortar and keep the fuel for something really useful.
- Cav rifle have their use on some specific maps, probably the best selling point of the doctrine atm.
- Combined arms requires an extra layer of micro of already micro intensive units. Combined arms is ok with the Pershing because the pershing can stand a bit on its own while you micro your infantry, that's not the case with shermans.
- Sherman 76 is bad on 2vs2 because its not better than a P4 and get bullied by panthers. So yeah you scared the first P4 built because you have better penetration but but then its not like you can chase it enough to kill it anyway.
-a You aren't necesarily in position to kill the P4. Just scare it off.
-b your AI is shit, unlike the P4 that can simply avoid you and keep a pak close by.
-c Panther join the party and your tank is rended useless.