Top draft pick Derek Rivers returns to Boston for further tests on injury

Rookie defensive end Derek Rivers will miss Saturday night's preseason game at Houston. Fred Kfoury III/Icon Sportswire

WHITE SULPHUR SPRINGS, W.Va. -- While the New England Patriots stayed at The Greenbrier before departing for Houston on Thursday, top draft pick Derek Rivers returned to Boston for further tests on his injured left leg/knee, which highlights how the team has a growing personnel issue at a defensive end position that was already thin at the outset of training camp after Rob Ninkovich's retirement.

Rivers was walking with a noticeable limp Wednesday after going down on a kickoff coverage drill in joint practices with the Houston Texans. Rivers had remained on the ground before having his left leg/knee evaluated by head athletic trainer Jim Whalen. Rivers ended up walking off on his own, but the team's plans to have him return to Boston for evaluation indicates that there is no final diagnosis on the severity of the injury.

So Rivers won't play in Saturday night's preseason game at Houston, nor will fellow rookie defensive end Deatrich Wise Jr., who sustained a head injury in Thursday's preseason opener. That leaves Trey Flowers, Geneo Grissom, Kony Ealy and undrafted Caleb Kidder as the next available players on the depth chart.

As for the big picture at defensive end, there is a question mark after Flowers. Rivers and Wise were always projected to be on the initial 53-man roster, but how quickly they might be able to contribute remains an unknown. Meanwhile, Grissom and Ealy have received a lot of reps in camp, and neither is viewed as a lock to make the roster. Kidder and fellow undrafted rookie Keionta Davis round out the depth chart, although Davis is not yet physically cleared to practice.

Where it all leads is one of the compelling personnel questions surrounding the Patriots, who as usual, are surely scouring the NFL landscape for possible reinforcements. The free-agent market isn't plentiful (could 37-year-old Dwight Freeney provide a boost?), but perhaps director of pro personnel Dave Ziegler can identify a trade target around the NFL similar to past years when the Patriots have added in-season reinforcements such as defensive tackle Akiem Hicks and linebackers Akeem Ayers and Jonathan Casillas.

One other aspect to consider is that the Patriots' defensive scheme is flexible, so outside linebackers could eventually be tapped to play more of an end-of-the-line role. Along those lines, undrafted Harvey Langi (BYU), who was moved to that spot early in training camp, is getting a long, hard look from coaches.

Between defensive end and depth at left tackle (starter Nate Solder has remained out with an undisclosed injury the past two weeks), the Patriots have looked a bit vulnerable at times in practice. Backup left tackle LaAdrian Waddle also went down with an injury Tuesday, and like Rivers at defensive end, he has also returned to Boston for further evaluation.

These are currently top personnel concerns facing the Patriots.