At the beginning of WW2 most of the major militaries still utilized animals as well as vehicles. Many of the vehicles of the day were not all that reliable or all-terrain until a few years later. Unfortunately for the allies the Germans had already developed the MG34 (precursor to the most excellent MG42) and the 8.8cm gun. The Allies weren't terribly out-gunned, but they were out-maneuvered and out-soldiered. Once again the ineptness of Hitler and some of the High Command saved the allies bacon and they didn't allow their field commanders (like Rommel) to be the very good soldiers that they were.
.
That's an excerpt from Mike Doubler's excellent book,
Closing with the Enemy: How GIs Fought the War in Europe, 1944-1945.
So, I'm not going to dispute that the Germans, on a soldier-for-soldier level, managed about a 4:1 kill ratio during the first part of the war, and were still working at something like a 2:1 at the end. But it's also a gross oversimplification to say, "Well, Hitler and the High Command saved the Allies bacon." There are a LOT of assumptions in that statement.
Let's start in the East, shall we? After the initial thrust towards Moscow, the Soviets _owned_ the Germans at the operational level of war. The Russians were maneuvering Armies (Corps to us) and Fronts (Armies to us) while the Germans thought at the tactical level. From the counter-offensive at Stalingrad until the fall of Berlin the Soviets. German tactical successes were rendered inconsequential.
German intelligence sucked, from the strategic level to the tactical level. At the strategic level a great example is the complete neutralization and doubling of the German intelligence network in England. Back East we can look at the Stalingrad counter-offensive. The Germans were caught completely off guard. Meanwhile the Soviets had gotten in close enough before the attack began that their maps had the locations of every heavy weapon in the penetration sectors pin-pointed. The Soviet scouts had been there and gotten back out without detection.
Let's go to the air. Of the 3,182 aces (five or more kills), the Germans dominate the top end of the score sheet and had 1078 aces. The U.S. has 1296 and the first U.S. fighter group (literally the 1st Fighter Group) didn't get to England until the summer of '42. Who had the better training program?
Finally, while the U-boat threat was significant, it was defeated by Allied tactics and technology. The German surface fleet made no significant contribution and certainly could not have prevailed in a trans-Atlantic war.
There's a much longer discussion to be had about poor production decisions (imagine if the Germans had just built PZIVH and Js and not wasted time on PZ Vs, VIs, made 88s instead of giant rail guns, and not even bothered with the V program, and the efficacy of Allied equipment (Garands, and the much maligned Sherman). And we haven't touched on superior U.S. artillery and CAS doctrine.