Mig-21bis 1972, is good for Air to Ground and worth it just for that alone, however Wiki quote says:
“The delta wing, while excellent for a fast-climbing interceptor, meant any form of turning combat led to a rapid loss of speed. However, the light loading of the aircraft could mean that a climb rate of 235 m/s (46,250 ft/min) was possible with a combat-loaded MiG-21bis not far short of the performance of the later F-16A. Given a skilled pilot and capable missiles, it could give a good account of itself against contemporary fighters. Its G-limits were increased from +7Gs in initial variants to +8.5Gs in the latest variants.”
IMO if it was operated in numbers like an Air force under CGI and used its radar for launching only, it would be a threat to the 4th gen fighters and would get its kills more so over defensive territory.