Lets leave the Italians out of this, they were a 19th century in a 20th century battlefield.
The German military as a whole, performed remarkably, revolutionizing armored and combined warfare. The commanders were excellent planners, but not good executioners. The most well known operations, the African Camoaign and the Blitzkrieg through France were thw execution of one commander, Rommel.
Operation Barbarosa was as much a military defeat as a political one. The army pushed far deeper than the supply lines could afford to supply. They engaged in seige warfare (At Hitler's behest, no doubt) removing their true advantage. Their formations went in blind, at times without any recon at all. The army must share the blame for operation barbarosa.
When you have this man as your head-of command what can you expect???
Same happened in Soviet Union. Stalin was more notorious than Hitler.
Dont forget what he did to USSR. Poor leadership was one of the main reason that Soviet troops were crushed heavily in start of Operation Barbarossa and Winters War. And it was caused by these-
https://en.wikipedia.org/wiki/Great_Purge
Purge of the Red Army in 1941 - Wikipedia, the free encyclopedia
When you have over smart leaders like them, you get screwed up, no matter how Brilliant you are.
Nope mate, Rommel was not the chief executioner of German victory in West Europe.
To say in details but in short- After WW1, France understood it cant with stand German invasion unless it is not supported by other countries, so they decided to make a huge Defense wall along Germany-France Border, known as Maginot like,
Maginot Line - Wikipedia, the free encyclopedia
Germans understood they cant overcome the heavily defended this line, so they decided at first to attack Belgium, Holland and Luxembourg. Their plan was to bypass Maginot line. As the Belgium and Luxembourg share a border with France, so they decided when French prepared for a possible German invasion directly from Germany-France border, and stationed their all equipment there leaving France-Belgium border completely undefended, then Germans would attack weak low land countries, these would be captured within 1 week, France would be shocked in this, and before French managed to divert it's troops to Belgium border, Germans would be already in Northern France, much like this WW1 era plan-
Schlieffen Plan - Wikipedia, the free encyclopedia
This was called Fall Gelb plan, how ever a sudden accident changed all.
Mechelen incident - Wikipedia, the free encyclopedia One German light plane, with on board of high ranking officers carrying documents of Fall Gelb, crashed inside Belgium, Belgium police discovered some part of the documents before Germans destroy those. France was alerted, French and British troops instantly moved to Belgium, Germany there fore changed plane.
Manstein Plan - Wikipedia, the free encyclopedia Erich Von Manstein, a German officer said now France is alert and it's troops are in Belgium, and now both Maginot line and Belgium is well defended, so Germany needs to launch a feint attack on Low lands, convincing them as French expected main German thrust is coming from Belgium, they would send their all military. How ever this feint attack's goal would be only to capture low land countries, then main German thrust would be launched through lightly defended Maginot line, as French already sent their military to Belgium, then Germans would advance through Belgium-French border, trapping French and British in low land while continuing their advance to Paris. It is in Short.
Among other best German Generals were Kesselring,
Albert Kesselring - Wikipedia, the free encyclopedia
and of course Guderian who made German Panzer divisions.
Heinz Guderian - Wikipedia, the free encyclopedia
You may find what I said in internet that may be too long, how ever these are the summarized version of what I read in Books.