In the NFL, there's an abundance of untapped potential, but it's not easy to optimize production, especially regarding rookies who are adjusting to pros.
In some scenarios, a roster rebuild could slow player progress. On a field with 10 teammates, synergy or the lack thereof can affect production. A first-year signal-caller cannot move the chains without quality pass-catchers. A majority of ball-carriers need a strong offensive line to attack run defenses.
In other cases, rookies have to simply play their way into bigger roles, which may lead to increased production. Lastly, injuries create opportunity—the next man up must fill the void.