There is an issue with Houston's NRG Stadium surface. Per Sports Radio 610 in Houston:

New England Patriots head coach Bill Belichick denounced it when then-wide (receiver) Wes Welker tore his ACL on it in 2010. A former Texans punter is suing the company that manages the field after suffering a career-ending ACL tear on it that he claims was its fault. Current Philadelphia Eagles players were critical after playing on it two weeks ago, questioning its safety and wondering aloud why the league won't step in and force changes

The punter is Brett Hartmann and his attorney said that the "maintenance of that field, the design of that field is an abomination. And it’s not just an abomination of how it looks, it’s the affect it has on these players." Battle Red Blog adds that Brian Cushing, Andre Johnson and Hartmann have all suffered significant injuries due to the stadium's surface. As did Denver's Von Miller.

"The turf down there is terrible," Belichick said on WEEI in 2010. "It’s terrible. It’s just inconsistent. It’s all the little trays of grass and some of them are soft and some of them are firm and they don’t all fit well together, those seams . . . some of it feels like a sponge, some of it feels real firm and hard like the Miami surface. One step you’re on one, the other step you’re on another. I really think it’s one of the worst fields I've seen."

"I definitely think they need to do something about it. We like the grass, but I think there definitely could be a better way to put the grass down," D.J. Swearinger told ESPN Radio in Sept. "When we go out there for walk-through, somedays we may see a hole and we ask coach ‘What’s going on today? Can they fix this?’"

"At issue is the way the management company, SMG, builds the surface by piecing together pallets of grass grown off-site, carted in and pieced together like a puzzle," writes Matt Hammond of CBS Local in Houston. "Critics say the process creates an uneven surface, with varying ground levels from one pallet to the next, and leaves seams where the pallets meet."

Our friends at Battle Red Blog, SB Nation's site that covers the Houston Texans, goes into more detail.

There are 1,400 pallets of 8' x 8' grass sections that form the football field at NRG Stadium. This design creates a patchwork field that features roughly 5,000 seams. The firmness of each pallet can vary greatly. Additionally, the edges and corners can separate, which creates a potential risk to players.

There is a belief that Jadeveon Clowney, who missed six games with a knee injury, stepped in one of the holes.

Texans S DJ Swearinger told me Jadeveon Clowney said in the immediate aftermath he stepped on one of "the holes" in the NRG Stadium field. — Albert Breer (@AlbertBreer) September 8, 2014

When asked about it on Wednesday, Bengals head coach Marvin Lewis wasn't worried about it -- in fact, he played the "I don't know what you're talking about" card. "Well the first that I knew that there was any issues was this morning, so I don't have any concerns," said Lewis. No word on if Bengals defensive tackle Geno Atkins sacrificed an animal to please the football gods. In other news, Lewis being blindsided by this only proves one thing... he doesn't have internet.