  We use some moment graph techniques, recently introduced by Lanini and
P\"utz, to provide a combinatorial description of the smooth locus in flat
linear degenerations of flag varieties, generalizing a result proved by Cerulli
Irelli, Feigin and Reineke for the Feigin degeneration. Moreover, we propose a
different combinatorial criterion linking the smoothness at a fixed point to
transitive tournaments.
