I will hazzard a guess that it involves compression ratio (I don't mean ratio of the compressor).
Refman tells 40/200 remember 200.
That's 4:1 CR ok.
Pumpdown to 15/200, now 7:1
Get to 0/200, thats over 14:1 !!
You reach a point where the gas trapped in the piston-to-valve area re-expands to totally refill the cylinder,... thus no new suction intake.