OKW starts with a bunch kubelwagen+assault engineers, which successfully forced the front. BUT 3+ squad allies, when the presence of micro successfully inflict serious damage to the kubelwagen and assault engineers - as a result forcing them to retreat for repairs. At this time volksgrenadier killed in skirmishes with arrows ( they reduce the distance to the middle and effectively kill hail of bullets), recruits ( 6 people behind cover they prestrelivaut ), prison battalions. Ie, if OKW resorts to using the machine gun doctrine calculations - area-60-70% remains for the allies. Means and resources more,and artillery closer. OKW is as far as I understand - efficient lightweight technology with the support of the small but powerful groups of professionals and medium-sized, numerous, universal volksgrenadiers. In practice, this concept is very lame, like the rest of middle class technology due to the abundance of at-weapons in the squads. And if the U.S., the Axis give ammo for heavy weapons squad, the USSR gets half for the requisition.
The recent changes at OKW turned it back into a viable faction again, having solutions to all game stages. It certainly doesn't need of further changes, not for now. The start is quite strong, and you may develop in the direction you want, chosing your core army on the way. You have the necessary tools for middle game and the proper tools for late game. Messing up with OKW now by implementing further changes may prove dangerous balance wise.
My 2 cents.