Philadelphia Eagles cornerback Nnadmi Asomugha was being evaluated for a concussion Monday night after leaving practice following an on-field collision with safety Nate Allen. Jeff McLane has the particulars here, and it's worth noting that Asomugha also suffered a concussion during a game in December. If he has another, it will be difficult to estimate the timetable for his recovery.

Concussions are serious business in today's NFL, especially with so many ex-players suing the league claiming it ignored the effects of head injuries for so many years. Concussions are also cumulative in their effect and the damage they do -- meaning a second one is by definition worse than the first. Should Asomugha have a concussion, the Eagles are likely to be extremely careful with how and when they return him to the field. And while it would see unlikely that the season opener 27 days from now would be in jeopardy, it couldn't be ruled out.

The good thing Asomugha has going for him is that the Eagles' medical and training staff has been influential in the establishment and administration of the NFL's concussion protocols, and for that reason there's no place better than Philadelphia for him to get whatever treatment and care he needs to make sure he doesn't return until it's absolutely safe for him to do so. He could be back in a matter of days, or, if he's concussed, it could be much longer. The long-term and short-term health of the player take precedence in these cases over team needs.

In the meantime, with Curtis Marsh injured, reports from up at Lehigh say that Joselio Hanson filled in for Asomugha after he left.

UPDATE (7:24 pm ET): The Eagles announced Monday night that Asomugha had no concussion symptoms, which obviously is encouraging news for his chances of returning to the practice field soon.