The Red Army wasn't really designed for a long-term general war with the west, since the thinking on both sides was that it would immediately escalate to nuclear arms. Rather, the Red Army was for
internal security, a force that would be capable of putting down individual nations/nationalities without ever having the logistical-political ability to carry out a successful coup.
And that sense it was very successful: they certainly had the ability to stop countries from leaving the Warsaw Pact and republics from leaving the USSR but Gorbachev ordered them to stand down. Even the coup attempt at the very end of the Soviet Union, (which involved high-ranking elements of the CP, KGB, and the military, not just the military) collapsed almost immediately. And if the KGB and the party hardliners had not been involved, it never would've even been attempted.