Just think of the MiG-25, which was a mythical superfighter that was supposed to single-handedly crush the entire NATO air force. The Americans, both on the basis of propaganda and according to their own dreams, feared it so much that they invested billions of dollars in air defense and aircraft to have an answer to it. Perhaps the most famous answer to the MiG-25 is the American F-15 fighter. In the 1970s, the Americans acquired the MiG from a Russian pilot, Belenko, who had absconded with it, and found the MiG-25 to be nothing more than a horrible superfighter that was miles ahead of not only the F-15, but also the older aircraft types.
Oh, and a few days ago the Ukrainians shot down a "modern" Su-34 (a bomber added to the 2014 armament) and interviewed the pilot, who incidentally is a famous Syrian butcher who took pictures with Putin and Assad, and he told them that they had about half of the airworthy aircraft on base. If this is how their new air force designed for the current war is doing, how about their reserve and older types?