I have been quite successful lately as US in 4vs4. I came from 2000 to around 400/300. Actually I'm mostly struggled when there is someone doing something very wrong in my team than losing because Axis players do it better or have late game advantages.
I'm an average player playing really preservative, not so much rusher, trying to hold territory and attack when I have a good opportunity. If you feel you're like me, check my BO below.
So let share some information.
This BO works pretty well in all 4vs4 maps.
You need to be aggressive at start. You need your mate next to you going where you go, because Axis players will do the same, there is no way to win your first engagement at 1vs2 because you or your mate next to you build a cache as 1st or second unit.
Do not send your RE alone to cap mid map, that's a stupid bet because same if you cap it first you cannot hold this territory with it.
Cap with your RE and make sure your 1st rifle and RE are together to engage and flank.
You have to be aggressive but not rushing, if your opponent set-up his MG and you cannot pass, wait for grenades, and flank with your 3 rifles squad + RE. Use and abuse of smoke, that the best tool you have early game, smoke MG or smoke bunker and go behind to cap.
Bring your ambulance close enough and soft retreat as much as you can. This mean, disengage faster if required to reinforce your squad closer.
If you are good with your unit preservation, you should be building at least 1 cache after your ambulance/lieutnant.
Bring your major close to your ambulance as retreat point.
Your first Scott is really important, do not lose it. in fact you should not be losing any vehicle at all. use it for smoke bunkers and MGs and attack with your rifles, Scott is an incredible indirect fire unit, keep it behind your rifle to rip blobs, use grenades when you can.
If you are good with your MP (and so your unit preservation), build an HMG, HMG + Scott do a very very good job. HMG suppress and scott decimate suppressed squads.
Your next unit is a jackson in any cases because P4s and Panthers are going to pop really soon, keep your jackson behing, and use it to keep them at distance.
Now is the moment of choice. It depends of what you have to fight, more blobs? go for a 2nd Scott. More Panthers or P4s, go for a second Jackson and next you go for your second scott or Jackson. It also depend of what your mate built. If he goes for mass AT, go for a Scott etc...
About the commanders. I like to go for Reco. It gives a reco sweep and a really good arty with IRPathfinders. Pop two for them, wait to have 300 munitions and take out any OKW building. If you don't plan to do it again, just sacrify one squad after that.
My BO doesn't includes Sherman. Why, because I believe they are too fragile vs blobs. Scott or Sherman are really RNG dependant vs blobs, sometime they hit, sometime not. So better to go for the cheapest option, it doesn't really require more attention since you leave it behind, you don't need to micro it like a sherman when you fight so you can concentrate on microing your rifles. Once Vet1, you have your smoke and it helps a lot to disengage.