Malik Murphy is a very physically gifted QB (mostly set to power run). However, he was seriously injured in his high school championship game. He's been rehabbing a long time, but I'm not surprised to learn he's still not 100%.
High ankle sprains are something I can speak on with more experience than I'd like. That's the least helpful description in sports. Could be a twisted ankle. Could be debilitating for an entire season or longer. All the ligaments that connect the foot to the leg do weird jobs. There's no "common" way they get hurt. They're all unique and take their own unique time frame to heal.
They're deceiving because the injury doesn't really show up until the next day. You know your ankle is hurt, and it's painful to walk on, but you can still do it. It's just very uncomfortable. I could jog and run peg-leg like even.
The next morning, once the tissue has had time to get inflamed and engorged, it's impossible to use the leg. The foot and ankle are swollen, and it hurts to be vertical or have the foot touch the ground. Recovery times are all over the map.