I think a top fighter moving down should need one fight to justify his spot but a guy moving up should not be granted the same grace. That said I have no issue with Edgar getting an instant shot since he has lost two controversial fights at LW for the title in a row and is moving down to a shallow division and its not about the credibility of Edgar as a challenger but more so about the fact that Edgar is more credible than any challenger and to a certain extent more credible than the FW champ. Edgar doesn't need credibility to fight for the FW title he adds credibility to the division by fighting for the title.
"If you get hit and it hurts hit him back you not knocked out yet."-Joe Doerksen
The Toxic Terrors (FFL)
Demetrious Johnson*Eduardo Dantas*Rafael Silva*Zach Makovsky*Michael Page