If you haven't rely on your Volks so much in the past you'd learn how to play proper combined arms with OKW, no you have to catch up the hard way.
Problem with this is that OKW has the most pathetic support weapons for combined arms. Raketens get instant decrewed by anything really. They fall into enemy hands very easily and are then retreated. The ISG cannot retreat like a mortar so it is also very easily decrewed. The Mg34 is pretty poor. No comparison to the other mgs in the game. That is your support weapons.
Then the mainline infantry are fragile. The pioneers are fragile and expensive. The elite infantry are also very fragile until you vet them.
When you put everything together, and add in the multitude of superior allied artillery strikes, it's just a very weak combined army that never really holds - which is why people whine about playing combined arms with the OKW.