Eli out with a "heel injury"

Remember Dan Marino rupturing his Achilles? IIRC he took the snap, dropped back to pass, and fell in a heap, with nobody near him. I saw a rugby player go down in very similar fashion recently - same injury. I haven't seen Eli's incident, but just because it looks innocuous, it doesn't necessarily mean it is innocuous.

Same thing happened to Billy Joe Hobert in a game against the Rams, season opener I believe. Just dropped back to pass and went down without being touch, ruptured achilles.