If he is a vet of the Battle of Stalingrad its impossible to overstate his achievement. He fought in a great battle that determined the course of human history. Had that battle been lost, the USSR would have fallen and the nazis would have had access to all of Russia's oil and its millions of men to draft to into service by force. Its impossible to know for sure what would have happened, but WW2 might have taken a wildly different turn. Stalingrad was the largest battle in history bar none, and one of its most important.

And in Stalingrad, largely it was reservists and freshly drafted conscripts with shit equipment joined by the rear echelons of the Red army, and Red air force, fighting the largest, best equipped, and most elite units the Nazis had, while the nazis were still fresh in the war, and running top-level high morale after winning a string of crushing victories that stunned the world.

Had even 1 bomb, or 1 artillery shell land on the famous T34 factory at Stalingrad the USSR would have been crushed in the war, left cripped and unable to manufacture their war-winning tank, and yet somehow fresh drafted farmer with 5 minutes of training crushed the best equipped, best trained, highest morale military force in the world at the time, the infamous Nazi SS.

And they NEEDED that factory. As the war progressed onwards it would build 55,000 tanks that were needed to replace battle losses to the nazis.

And I believe its fully possible to sing the praise of the common soviet solider even if Stalin was evil. Stalin didn't win the BoS, it was men like these, ordinary people who wanted to live in peace but answered the call to defend their homelands.