PPRUNE Fan,
You are correct in saying that high ROD does not in itself cause VRS. It is however a contributing factor along with low airspeed and power applied. With the V-22 in question not getting below 40 KIAS and a low ROD was observed it seems that it was outside this criteria but the nacelles were back at 95 deg and the aircraft was decellerating. This would cause a large component of airspeed opposing the induced flow thus providing the required real ROD through the discs. The V-22 is always going to suffer from AsymVRS as VRS is an unpredictable thing and one disc will always reach it before the other causing the wing drop which when compensated for will increase the effect whilst reducing the effect on the other disc.