I was not in front of the screen so I can't recall the second play you mentioned, but I would make a humble argument on the first play about Simmons misreading the play. He turned and covered the TE immediately after the snap, while Kennard who lined up against that TE at the LOS went rushing the QB. To me, that seems like Simmons was doing his assignment by taking the spot where Kenard vacated. If he did not go cover the TE, he would be wide open on the sideline. Nobody can tell whether it was a pass or run play from the beginning with the formation. Seattle has 2 receivers and 1 TE lined up on the LOS. Russel could very well keep the ball and pull out a play-action play. Simmons was not the only one, Kennard thought it was a play-action pass play as well as he stopped rushing halfway and clogged the passing lane.
Hicks could also share part of the blame as he might slide the right side too much, which caused him to be blocked by the guard, and was not able to come back to the tackle Penny. There could have been a miscommunication between Simmons, Kennard, and Hicks. With all three of them going spread to different sides of the line, the middle to the left side was left wide open. I actually do not see how the cardinals could stop that play with how they lined up unless:
1. they recognized the run paly from the get-go (nobody on the team did), or
2. Hicks stayed put instead of sliding to the right side, but Penny might break on a run on the right side (all Cardinals players on the right side were blocked as well) or
3. have Baker closer to the LOS to clog the open lane on the left, but Wilson might do play action and go deep, who knows.
Would Simmons know better with more film study, maybe, but I would not blame Simmons on that play. Seahawks designed and executed a great play that countered our defense scheme perfectly and that's it.