  In light of the latest neutrino oscillation data, we revisit the minimal
scenario of type-I seesaw model, in which only two heavy right-handed Majorana
neutrinos are introduced to account for both tiny neutrino masses and the
baryon number asymmetry in our Universe. In this framework, we carry out a
systematic study of the Frampton-Glashow-Yanagida ansatz by taking into account
the renormalization-group running of neutrino mixing parameters and the flavor
effects in leptogenesis. We demonstrate that the normal neutrino mass ordering
is disfavored even in the minimal supersymmetric standard model with a large
value of $\tan \beta$, for which the running effects could be significant.
Furthermore, it is pointed out that the original scenario with a hierarchical
mass spectrum of heavy Majorana neutrinos contradicts with the upper bound
derived from a naturalness criterion, and the resonant mechanism with
nearly-degenerate heavy Majorana neutrinos can be a possible way out.
