So the only progress defensively is cosmetic. The weaknesses evident in the 1970s have not been corrected rather after a slight improvement have been replaced by offensive, feel better,strengths - PK goals. Different make-up in a cosmetic attempt to hide the ugly side of Soviet overall defensive weaknesses including the PK.
Regarding these defensive weaknesses of the Soviets it is interesting that Canada/NHL let in clearly more powerplay goals against the Soviets than the Soviets did against Canada/NHL in best-on-best competition between the 1972 Summit Series and the 1987 Canada Cup. Seems like Canada also could have needed some cosmetic attempts to hide the ugly side of their own defensive weaknesses. Before someone jumps down my throat about it I want to point out that this last comment was obviously only sarcastic. However I do think that a very good case can be made for that the Soviet penalty kill actually outperformed the Canadian/NHL penalty kill over a rather large sample of games during the 1972-1987 time frame. This does not mean that the top Soviet penalty killers were superior to the top Canadian penalty killers of that time frame but it is in my opinion a good indication of that the top Soviet penalty killers definitely belonged among the best penalty killers in the world at the time.
Soviets versus Canada/NHL (Summit Series 1972, Canada Cup 1976, Challenge Cup 1979, Canada Cup 1981, Canada Cup 1984, Rendezvous 1987, Canada Cup 1987)
USSR: 8 shorthanded goals forward, 14 powerplay goals against, goal differential -6
Canada/NHL: 1 shorthanded goal forward, 19 powerplay goals against, goal differential -18
And here is the tournament by tournament breakdown.
Summit Series 1972
USSR: 3 shorthanded goals forward, 2 powerplay goals against, goal differential +1
Canada: 1 shorthanded goal forward, 7 powerplay goals against, goal differential -6
Canada Cup 1976 (1 USSR-Canada game)
USSR: 0 shorthanded goals forward, 1 powerplay goal against, goal differential -1
Canada: 0 shorthanded goals forward, 0 powerplay goals against, goal differential 0
Challenge Cup 1979
USSR: 1 shorthanded goals forward, 2 powerplay goals against, goal differential -1
NHL: 0 shorthanded goals forward, 3 powerplay goals against, goal differential -3
Canada Cup 1981 (2 USSR-Canada games)
USSR: 1 shorthanded goal forward, 1 powerplay goals against, goal differential 0
Canada: 0 shorthanded goals forward, 3 powerplay goals against, goal differential -3
Canada Cup 1984 (2 USSR-Canada games)
USSR: 0 shorthanded goals forward, 1 powerplay goal against, goal differential -1
Canada: 0 shorthanded goals forward, 2 powerplay goals against, goal differential -2
Rendezvous 1987
USSR: 0 shorthanded goals forward, 2 powerplay goals against, goal differential -2
NHL: 0 shorthanded goals forward, 1 powerplay goal against, goal differential -1
Canada Cup 1987 (4 USSR-Canada games)
USSR: 3 shorthanded goals forward, 5 powerplay goals against, goal differential -2
Canada: 0 shorthanded goals forward, 3 powerplay goals against, goal differential -3