Injuries are injuries, I really don't think Dak can be "blamed" for the one he suffered last season.
Interceptions however: some portion of that blame can be put on the results of poor play-calling, situational football. Dak deserves *some* of that blame, for sure. But not all of it, for sure. If your scheme is putting the offense in 3rd-and-long situations too often, you will for darn sure start to see more aggressive pass attempts to move the chains, and this will indeed lead to more INTs.
It's not a mystery, and it's not complicated: football is more "team-sport" than any other team sport. What the o-line is doing, what the receivers are doing, what the running game is doing, and even what your defense is doing - all affects QB performance. As does the QB himself, of course.