I never looked deeply into World War One as a conflict so this question's premise very well may be somewhat incorrect, but I never could figure out why Austrian armies did so mediocre in comparison to Germany despite usually fighting side by side with them against their main adversary (Russia). From the point of bystanding observer it almost looks like Germans had to redirect additional forces just to save their partner.
1914, battle of Galicia - complete Austrian defeat, Russian occupation of Galicia, Austrian losses are very heavy and exceed those suffered by Russians.
1915, Great Retreat - despite Russians having terrible leadership and lacking meaningful firepower, Austrian troops again suffer noticable casualties - bigger than those suffered by the Germans.
1916, Brusilov's offensive - offensive has great momentum at the beginning, forward Austrian forces are routed, but the Russian army is later stopped by Germans at Kowel.
Italy - Austrian forces hold Italy off pretty well but are later defeated and have to withdraw until Italian army gets defeated by Germans at Caporetto.
You can argue that these defeats happened due to Russian and Italian numerical superiority, but it didn't stop Germans from defeating Russians at Tannenberg and conducting successful offensives against both British and French while lacking in numbers.
What were contributing factors that led to AHE's combat performance? Or do I simply get my facts wrong?
This is an outcome of a few different factors, some from pre war failings, some during the war, and some structural the the Empire.
The pre-war failings come down to preparation. The Austro-Hungarian Empire, mostly due to Hungarian obstruction, spent less money per capita on military expenses than any other major or mid size power in Europe. They spent roughly the same amount (per capita) as Italy (insert eye roll here) and Russia (who had far more people). On a different scale, they sent FAR less on the military relative to their GNP at the time. Close to 50% of Russia on a similar scale, and around 3/4 of the other major players in the coming war. (Max-Stephen Schulze, in "The Economics of World War I, Broadberry and Harrison, Schulze is citing Stevenson in "Armaments and the Coming of War: Europe, 1904–1914")
This lower level of investment had several effects down the chain:
The expression of this failing was that in August 1914 Austria could only field a maximum of 2.3 million men under arms when it called up everything it had (including the Ersatz militias). As Schindler cites, France had a population roughly 10 million less than Austria (something like 20%) and put 4 million into the field (without dipping into their Ersatz equivalents). Then, when Conrad pissed away everything in Galicia in the fall 1914 and the Karpatenkrieg campaign in the Winter, the Empire had no pool of men with recent military training to fall back on for replacements. The Austro-Hungarian army, which gave Russia some good fights early in 1914, was very literally a militia force by March 1915 and their performance reflected as much the rest of the war.
Further on leadership, the Empire had only, on average, 3 NCOs per company in the start of war force. Germany had 12, France had 6. (Schindler, again). So not only did Austria not choose to promote new officers from the ranks of experience NCOs, they didn't even have that many NCOs to choose from or to help the inexperienced new officers govern their new command. Especially after the terrible losses of the first 8 months.