I don't know, I can't speak for their military leaders, but I've read Soviet physics papers and they had (funded and educated) some solid scientists.

Physics as a field doesn't have the same pressures and people aspiring to it as intelligence military analytics.

While I agree intel and physics are apples to oranges, the soviets had a pretty good intelligence arm and quite capable analytics. The soviets where very good at Human Intelligence:

http://sputniknews.com/military/20150928/1027670037/kgb-cia-...

Yeah, nothing tells true stories about KGB like the face of modern Russian propaganda machine.

The facts are easily verifiable read about Yuri Totrov. It is well documented by both sides.

Also in physics, you can't get away with politicking and reading the Party plenary speeches alone. That nuke better has to work and is easily verifiable: Beria, the head of Soviet secret police, personally compared the mushroom cloud photo of the U.S. test to the Soviet one, to ensure the bomb was copied correctly.

I wonder what he'd have concluded if it had looked different?!

That the discrepancies were the work of wreckers and saboteurs.

Probably followed by liquidation of the parties responsible.

It's more about "how can we waste their time" than it is about competence.

Don't underestimate either. Soviet/Russian rocket engines are still better than American.