My problem with that is that every player has flashes in the pan while developing. These are the glimpses of what they can become, and if they're developing well it's because they are having those flashes more and more. Roope Hintz, Troy Terry, Alex Tuch, Jakub Vrana as examples.
The guys that backslide in their development are the kinds of guys that show those flashes less and less in the pro game. Guys like Brendan Smith, Tomas Jurco, Evgeny Svechnikov (to a lesser degree), Teemu Pulkkinen, Jesperi Kotkaniemi, Logan Brown.