The NFL regular season is more volatile on a week-to-week basis than the Stock Market. One team that lost by several touchdowns the week before can follow up with a blowout victory. Players who are responsible for the blame one week could be responsible for a game-winning play the next.

With Week 4 in the books, let's take a look at three NFC East players who saw their stock rise, and three NFC East players who saw it fall as we head into Week 5.

Three Up

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Kirk Cousins, quarterback, Washington Redskins

Kirk Cousins is an improved player in year two under Jay Gruden's offensive scheme. If you want your proof, just take a look at his performance in Week 4. Cousins led the Redskins on a 90-yard game-winning touchdown drive with the Redskins trailing by 4 points. He capped off the drive with a perfectly placed 4-yard touchdown pass to Pierre Garcon.

Rashad Jennings, running back, New York Giants

During the offseason, there was chatter that Rashad Jennings would be phased out of the Giants' offense after beat reporters saw him practicing more on special teams and less with the first team offense. In Week 4, he proved why that would be a major mistake and why it's something the Giants have not actually considered. Jennings turned a 2-yard outlet pass into this 51-yard touchdown catch by making multiple defenders miss and rag-dolling a defensive back to the ground with an excellent stiff arm. Jennings finished the game with 92 total yards, once again proving why he deserves a major role in the offense.

Trent Murphy, outside linebacker, Washington Redskins

The Redskins drafted outside linebacker Preston Smith this offseason with the intention of having him split snaps with Trent Murphy at right outside linebacker. If Murphy continues to play like he did in Week 4, they might have to rethink that. Murphy split snaps with Smith, but even in limited snaps, he was the best defensive player on the field. He racked up two sacks and three quarterback hurries. As he always has since entering the NFL, Murphy also did an excellent job of setting the edge and making stops in the running game.

Three Down

Joseph Randle, running back, Dallas Cowboys

It's never a good thing when you get reprimanded by your head coach for a mistake only to make the exact same mistakes the very next game. In Week 4, Joseph Randle did just that. Cowboys head coach Jason Garrett was not too pleased with Randle's decision to reach the ball out and nearly fumble on first down from the opponent's 1-yard line -- he had discussed the scenario with Randle prior to Week 4 after Randle made a similar decision in Week 3. After Randle's near-fumble in the first half, he saw just four more carries the rest of the game.

The entire Eagles offensive line

The Eagles offense has struggled through the quarter point of the 2015 regular season thanks to several factors. The biggest culprit for their slow start has been the play of their once dominant offensive line. Head coach/general manager Chip Kelly replaced the players he got rid of at the skill positions with new talent, but he neglected addressing the offensive line after losing both starting guards from 2014. After grading out in 2014 as the best best run-blocking unit and a top 10 team in pass protection, per Pro Football Focus, they are in the bottom half of the league so far this season in both grades. With injuries across the line and replacement-level players at both guard positions, there is reason to be skeptical of a quick turnaround.

Andre Roberts, wide receiver, Washington Redskins

Andre Roberts signed a four-year, $16 million contract with the Redskins last offseason. He went on to finish 2014 with the most drops (7) of any slot wide receiver. After being promoted to the starting lineup this season, following an injury to DeSean Jackson, Roberts struggled with drops and poor route running in his expanded role. In Week 4, head coach Jay Gruden decided he had enough -- Roberts was a healthy inactive and Ryan Grant took his spot in the starting lineup.