IOT the Germans did about as well as they could reasonably have hoped. The potential for victory was there but always just out of their grasp. I think a good POD for an ultimate CP victory is that instead of attacking Verdun Falkenhayn decides to a coordinate a grand offensive against the Russians with the Austro-Hungarians. This would forestall the great debacle that was the Brusilov Offensive for the Austro-Hungarians as well as remove their pointless and stupid Italian offensive. Another year of crushing defeats might cause the Russian war effort to collapse sooner than it did IOTL while keeping the Austro-Hungarians in the game longer.
The downside is that no Verdun means a better coordinated Somme offensive with proper French support for the British but I think in the end the Germans withdraw to the Hindenburg Line regardless and the French and British could be expected to go no further. So in the end avoiding Verdun might put the CP in a better position to finish off the Italians in 1917 and then focus on British and French.
Well a lot of people agree with this, Churchill and Hitler included. The tricky part is that they would want to wait until June for the weather to clear. The CP didn't like Winter offensives after the 1914-1915 losses. Verdun allows the Germans the ability to do something right now.