Germans Changed Tactics
Around every 100 deployed German troops, the Germans change tactics.
What does this mean? Well, they figured out that sending mindless waves of people did not work, so they send a BIG mindless wave of people at you.
However, there is a good side to this. When it occurs, it wipes all other German units from the map, including units spawned by a Blitz Wave and Wespes, so these are a double edged sword. They can completely devastate you, or they can really save you. Although they are nothing more than grunts, they may throw their grenades in masses if you don't have an effective anti-infantry setup, and can wipe out your men and damage your vehicles. However by the time the Germans change tactics, you should be in a good position to kill them all. If you are running low on options, a CAS can help you.