My point being, Diplomacy does little to represent the capabilities of the nations involved. But I'll entertain a fun one- can Germany, for example,open up a two-front war in the early stages of the game? Say Germany sent only 1 unit east, relying on his allies to bear the bulk of the Russian front, with strong diplomacy he could potentially take Warsaw and 2 neutrals in 01.
However, if the situation is similar to ww1, England might let Germany waltz around, but France isn't. France is still sore about the Franco-Prussian war and believes it can win a glorious victory for honor. France will certainly open to Burgundy, where it historically raised fortresses on the German border. Thus, Germany will need to cover Munich, and will have potentially 2 builds(Warsaw+one of den/hol/bel), to Frances also potentially 2 builds(spain and portugal if he supported Par>Bur and opened to MAO)
England meanwhile should have supported himself into Norway. Russia should be in a bad way, Austria and Turkey should be doing well. If the central alliance is to continue Germany will probably get support into Moscow to bolster him against France.
Bolstering he will need, because without an ally to France's East, Germany has decided to attack France through Belgium. At this point, an optimistic center count would be Germany with home+Den+Warsaw+Moscow+Bel. France has Home+Iberia, England Home+Norway. Sweden and Holland could be occupied by either side.
Thus, with an incredibly enthusiastic Austrian ally, a quiet turkish ally, neutral Italy, and timid England, I'd say Germany has a chance of winning the war in the East and turning to successfully fight France and England, with limited support trickling in through the Med, possibly even the Alps and Scandanavia. The timing of the Italian entrance to the war could be decisive. If he waits until Russia is knocked out of Sev, its probably too late.