The men who run SB Nation's USC blog, Conquest Chronicles, are kind enough to pop in from time to time to offer support for their guy, Mark Sanchez. They also have an extensive inventory of articles discussing football injuries. They have a report on Achilles tendon injuries.
Achilles Tendon Rupture
This is commonly an acceleration injury e.g. pushing off or jumping up. The classic example is a middle-aged tennis player or weekend warrior who places too much stress on the tendon and experiences a tearing of the tendon. In some instances, the rupture may be preceded by a period of tendonitis, which renders the tendon weaker than normal.
An Achilles tendon rupture is usually an unmistakable event. Some bystanders may report actually hearing the snap, and the victim of a rupture usually describes a sensation similar to being violently kicked in the calf. Following rupture the calf may swell, and the injured person usually can't rise on his toes.
This in the injury that Vinny Testaverde suffered on opening day in 1999. Dan Marino also suffered one in 1993. Their mobility appeared much more limited after it happened. This medical analysis taken shortly after Testaverde's injury indicated a 6-12 month recovery window and perhaps a 90% recovery if things went well.
Woody is clearly up against difficult odds.