The line which says 80% availability across all aircrafts much bigger achievement than just for the flanker fleet..63% is not good at all especially when you don't have enough of them and face a bigger threat to the north with a massive flanker/4th gen fighter fleet.
No. Should could doesn't cut it. India would be boasting if their Flanker fleet MCR was close to US F-15's but they don't because they are not. India is an importer of fighters and parts depending on other nations to keep their fleet fly worthy this is why India's flanker fleet MCR is likely still in high 50% to low 60%.
Where does it say Flanker? Doesn't even say how many flankers took part if any.