Yes, but performance-hindering injuries are extremely common, which is what i'm referring to here. Guys like A-Gon, Rodriguez, Crawford, Pujols, CarGo and Tulo all signed monster extensions and have seen either their production or games played negatively impacted by specific or nagging injuries.
Tulo and CarGo, in particular, are cases of young guys who just seem really injury prone but got massive extensions anyways.