ORIGINAL: Pelton
The Germans were winning the war of atrition through 41 into 42 as can clearly be seen by Russian losses through early 1943.
Red Army Losses
---------------- Killed+Wounded KIA+Missing
1st Quarter 1942 1,800,000 620,000
2nd Quarter 1942 1,500,000 780,000
3rd Quarter 1942 2,400,000 1,140,000
4th Quarter 1942 1,390,000 456,000
1st Quarter 1943 2,077,000 656,000
Pelton
In this period in which the Soviet Union was "clearly losing" the attrition war the Red Army strength increased from 2,818,500 (1941 4th Quarter) to 6,459,800 (1943 2nd Quarter)
Source: Glantz and House, "When titans clashed", Appendix, Table A. The same source shows the very same losses shown by Pelton (for instance, 1st Quarter 1943 656,000 killed or missing; 2,077,000 is the TOTAL (including wounded and sick). Maybe he forgot to mention the first column of that Table A (average strength).
Table C in that book shows that the strength ratio Soviet:Axis was 1.34:1 in March 1942 and 1.68:1 in April 1943