OKW always seem strong at a glance because all of their stuff is the best at just being thrown at a cap point. Their tanks have the best frontal armour and their infantry are the best for just running and gunning. So if you are also just running at the cap as well, they are gonna win every time, it's what they're designed for. Once you start playing smarter they kinda of fall apart due to their flaws.
This is the thing I was trying to highlight - it's very much in the hands of the allies to have to outplay OKW. All other things being equal axis come out on top. They can throw well trading units at you and wait for the late-game powerhouse.