I would include the mass surrenders at Stalingrad and Tunis into the operational equation, the same with the encirclement and destruction of 4. Armee at Minsk, or most of 6. Armee in Romania, and also Falaise. Pretty much any German surrender before 8/9 May 45 (and allied surrenders depending on their relevant dates) I would attribute to an operation. Given that, I would be very surprised if even after adjusting for changed force ratios, this period would not look an awful lot worse for the Germans then Fall Gelb, the operations of AG Centre and AG South during Barbarossa, or Kharkov 1942. But maybe I am wrong in my assumption.
I am not at all sure, given that the force relation changes more strongly than the casualty ratio. But here we are all groping in the dark, as there is AFAIK no methodology in existence that could guide such an assessment. If one just makes a "raw" comparison, it seems to raise far more questions than it answers: For what it's worth (which almost certainly ain't much), this a purely nominal overview of the combat losses in the East, where the quarterly force ratio have simply been multiplied with the quarterly casualty ratio:
1:1.2 1:4.8 5,76 3q41
1:1.1 1:5.4 5,94 4q41
1:1.7 1:5.9 10,3 1q42
1:2.0 1:6.2 12,4 2q42
1:2.0 1:6.0 12 3q42
1:2.2 1:7.0 15,4 4q42
1:2.1 1:3.8 7,98 1q43
1:2.3 1:3.9 8,97 2q43
1:2.4 1:4.9 11,76 3q43
1:2.5 1:5.0 12,5 4q43
1:2.6 1:4.4 11,44 1q44
1:2.6 1:3.1 8,06 2q44
1:3.1 1:2.0 6,2 3q44
1:3.6 1:3.6 12,96 4q44
Primarily a pretty good illustration of your previous point concerning the need to understand why
these figures are as they are, and quite possibly an altogether pointless exercise.
One thing that is very clear from the above (from the casualty ratios alone) is that major annihilation battles often has a major effect on the macro casualty exchange ratios, which is one of the reasons why it is difficult to apply the same type of analysis to higher levels. Interestingly, this seems to be the case primarily for the Soviets: there are marked improvements in the period where the Stalingrad losses were written off, and even more during the summer of 1943. There is no corresponding effect in periods of major German annihilation victories. Quite possibly this in itself could tell us something interesting about the two armies. I wonder just what though.
But in any case, what also appears to be important to me is that there is a difference between efficiency and effectiveness that is often overlooked when throwing around casualty exchange ratios (present company excluded). The Germans in early war were more efficient than their opponents and effective (in the sense of losses as proportion of force when achieving the desired outcome). By late war they may still have been more efficient, but they certainly were not particularly effective anymore, since (I assume) they lost a higher proportion of their forces, while not achieving their goals anymore. Also something to keep in mind.
Of course - "effectiveness" and "efficiency" can be understood as two different things. I think that usually the distinction isn't observed, and most people simply mean the latter.