Frederick the Great, King of Prussia, made a name for himself and Prussia in the Seven Years' War, winning key battles against the French and Austrians at long odds. He won the battle of Rossbach against the French outnumbered almost 2- to -1. Other Prussian generals beat the French at lesser odds at Krefeld and Minden.
Frederick beat the Austrians at his signature battle at Leuthen, outnumbered more than two to one. One might attribute this to the incompetence of the Austrian commander, Prince Charles of Lorraine (Maria Theresa's brother in law), but Frederick also defeated the Austrians at Liegnitz and Torgau, at lesser odds, later in the war.
The one enemy Frederick had no success against was Russia. The battle of Zorndorf, (aptly named "angry village" in German), where both sides took around 40% casualties, was basically a drawn battle, and at best a Pyrrhic victory for Frederick. At the battle of Kunersdorf, where two thirds of the opposing force was Russian (the remainder Austrian), and the numerical odds nearly even, Frederick suffered a major defeat, trying to turn a likely minor victory into a major one. And so far as I know, neither Frederick nor any of his subordinates won any victory to speak of against the Russians. Only through the death of Tsarina Elizabeth was the Russian threat mitigated.
Why might that have been? Were the Russian soldiers better than the French and Austrians? Were the Russian commanders better? Or did the Russians fight in a style that Frederick didn't understand?