We told you on Sunday evening about Rams receiver Mark Clayton’s disappointing season-ending injury.

Now we can tell you exactly what he got injured. ESPN’s Adam Schefter reports Clayton suffered a torn patella tendon in his knee.

It’s a particularly cruel injury for Clayton, who was about to enter free agency for the first time at 28 years old.

It’s another reminder how fast things can change in the NFL. Yesterday morning, Clayton was one of the top ten receivers in the NFC and the Rams felt great about their chances in a soft NFC West with an up and coming defense. Reality hit hard with this injury and a 44-6 beatdown in Detroit.