An NFL draft class is ever-evolving.
Preseason expectations based on the previous campaign's performance often change. Individuals can impress or disappoint throughout the regular season and playoffs.
Once collegiate games are complete, incoming prospects then have all-star festivities, the NFL combine, medical evaluations, interviews, pro-day workouts and private meetings/workouts to make an impression.
As such, static evaluations aren't realistic. For those evaluating the event, a constant flow of information and study must be undertaken from August through April.
The Bleacher Report Scouting Department takes this task seriously. B/R scouts Brandon Thorn, Cory Giddings, Dame Parson and Matt Holder work throughout that period, getting eyes on as many prospects as possible and constantly rechecking their assessments.