I am actually of the opinion that short of Entente lead drinking or German friendly ASB’s, Germany cannot win after 1914, and even 1914 is iffy at best.Without an American intervention, is a 1918 victory in the cards?
The German Army had many things going for it. They tended to learn at least marginally faster than their opponents, they maintained a higher tempo than their opponents and , on the Western Front, the strategic situation allowed them to use the power of the defensive. Just to name a few.
But no amount of any of those advantages were enough to make up for the strategic and diplomatic situation that Germany had found herself in. German political and diplomatic failings in the 2 decades (or more, depending on how you look at it) prior to WW1, encouraged by military thinking that gambled everything on an ability to return to battles of annihilation, basically wrote cheques that Germany could not cash.
Even without American Entry, chances of German victory had long past by 1917-18. German leadership could perhaps have taken the hint and used the territory they did hold to bargain for a more lenient peace terms. But if the German leadership system was equipped to do that, they probably would not have gotten themselves into the situation in the first place. And even then, it would have taken considerable convincing on the Entente side.