Nope, achilles and patellar tendon are the two leg injuries that I wouldn't bet on anyone making it back from. Especially an injury-prone RB with a big chunk of mileage on him. I wouldn't offer him more than the vet minimum deal with incentives as a TC flyer.
If it was just a torn ACL, I'd be really intrigued. And admittedly, his running style is probably more able to weather the effect of injuries than other guys, since he doesn't rely all that much on burst (compared to other RBs) to begin with. But you still need to have some, torn achilles seems like basically a RB death sentence to me.