Just because India is buying it doesn't make it third grade weapon. Your allies China and Turkey are also planning the procure this weapon system.
I am pretty sure S400 will be protected by other SAM systems albeit with smaller range. Probably Tunguska will be at it's inner most ring!
@Major...
We are not doing it for free and reason small companies prefer ISRO is the low cost it asks for launch. This is also the reason you don't hear USA/Russia doing this as they charge too much and small companies are not able afford it. Low cost space launches is the way forward to enable...
I guess in red flag they simulate everything. This is what I found. Maybe someone else can tell!
https://theaviationist.com/2017/02/05/f-35s-kill-ratio-with-aggressors-stands-at-151-during-red-flag-17-1-most-probably-thanks-to-the-supporting-f-22/