Well if half of the crashes are due to pilot error, you can't blame the aircraft as much. What you can perhaps infer, given more information, is that having a robust and avionics systems providing better situational awareness could potentially help the pilot in catching their error or might even course correct the aircraft itself. F-16s are also a few generations ahead of in terms of engine technology and their engines have been updated by the manufacturer repeatedly over the decades to make them more reliable and efficient.
The same is not true for either the Mirage or the Mig-21, that have had no real updates, especially by their OEMs in 30-40 years.
As for the crash rate, in the last 9 years we have had 17 Mirages and 15 F-7s of varying types crash, along with 2 JF-17s, so give or take 4 crashes a year. That is not such a track record for a large air force like the PAF that has a fairly high flight tempo.