Purges and infrastructure both crippled Stalin's fleet

Was Stalin's big fleet hurt more by the Great Purge or by lack of infrastructure?

Both: infrastructure was the surface problem, but purges removed the people who might have fixed it.

Asked whether purges or infrastructure were the bigger barrier to Stalin's big fleet, the answer is that the two reinforced one another. Infrastructure was the visible constraint, but the people who might repair that weakness were repeatedly removed. Docks, yards, and production capacity could not be treated separately from the engineers, administrators, and officers needed to improve them. Soviet naval ambition therefore did not translate cleanly into a balanced, mature fleet before the Second World War.