No. Just him.
The majority of young players will improve as the season progresses. Parsons late season stats tell a different story.
For example, let's look at sacks, although, you could use forced fumbles, quarterback pressures or tackles for a loss:
In his three seasons combined, Parsons averages .92 sacks a game through the first 10 games of the regular season. That's almost one sack a game. In games 11-17, he averages .46 sacks. In the playoffs, he averages .25 sacks a game.
The later the season, the more important games become for playoff positioning. Then there is the single elimination playoffs. By that point, Parsons is noticeably average.
Parsons is clearly worn down by the end of the season. His body was not built to endure the pounding he receives on the D-line and he has lost valuable experience he should have been gaining as a legitimate LB.
As his career continues, so will this statistical trend. He will begin to wear down earlier and earlier each season. It is true that he is not the next Lawrence Taylor. However, he could have been.