My German language teacher in high school was a nice guy. Everyone liked him. It was easy to be buddies with him. The homework was super easy. Kids in the back got to do whatever they wanted during the period (I was one of them, though I was usually doing homework for a more serious class). I think we spent four periods that year where we played "German" kickball (ostensibly, you were supposed to speak nothing but German while we all played a game of kickball - and remember, we're in high school... kickball... for high schoolers...).
You could learn if you really applied yourself and tried hard to care more than the teacher.
By way of analogy, I guess that's what we saw in guys like Donald, Hekker, Zuerlein, and Gurley (for one year). They cared more than Fisher, so they played well. But they were the few on a team that didn't care more than their coach... and why should they?
Today, the only German I know is the same German everyone else knows. "Wienerschnitzel." "Verboten." "Schutstaffel" (couldn't tell you what that means, but that's what enemies in Wolfenstein 3D yell at you).