So I think that there are a few issues here. First, generally speaking, you should expect higher casualties from the force on the offensive. This didn't necessarily bear out in the early part of World War II, where the Soviets were suffering from just about every manner of problem you can think of, from logistics, to training, to leadership. In the latter part of the war though, with the Germans on the defensive, as you would generally expect, the defensive force was generally able to inflict higher casualties on the attacking force, especially in situations like the Battle of Narva which were conducted on a rather narrow, easily defended front.

Now, more far importantly though, while you are focusing on a few specific battles, on the whole, the Soviets were taking less casualties in the latter part of the war, when viewed overall, instead of a few snapshots here and there. Here are the Red Army Loses by Quarter from the beginning of the war till the end. The numbers are taken from the appendix of David M. Glantz and Jonathan House's "When Titans Clashed", but the percentages are what I got from plugging the numbers into an excel sheet.

So what I hope this illustrates here is that contrary to the impression you have from a few battles here and there, the trend for the Red Army in terms of loss rate was on a generally downward trajectory.