I've read several places with people commenting that Myles Jack is worth the risk because Brett Favre played 20 seasons with a hip condition that doctors said he wouldn't last more than 3-5 seasons at best. Brett cited it as "It's a lack of blood supply to a socket,". Myles Jack said on April 15 "no one had any concerns" when he got his knee checked. He admitted April 27 he may need microfracture surgery on his knee. Some are saying Myles won't last 5 seasons.
The huge distinction here is obvious, so obvious that the comparison should never be made. Brett played quarterback and had five large men creating a pocket for him stand upright where as Myles needs to be running sideline-to-sideline driving his shoulder into ball-carriers is constantly stressing his knee.