I will first off tell you when I was watching the game live, that I was shocked and laughing sarcastically that KF kept sending Petras back out there. It really did look like Petras was THE problem. However, while it is obvious that Spencer did not have his best day and missed some throws, there is much more underneath the surface after the rewatch (and pausing, and rewinding, and slo-moing, etc.).
Offensive line
This offensive line is truly offensive. It is, in my opinion by far and away the worst offensive line of the KF era. I understand that of the 5 players that started that 2 of them played in their first game and the other 3 are playing for the 2nd year. Lots of youth there, I get it. But, they were completely and dominantly out-played by an undersized (by FBS standards) defensive line and shown to be slow, weak and on top of that a rag-tag bunch that really doesn't have an idea what they are doing. And know this: SDSU, an FCS team, played us straight up the entire game!!! Don't let anyone tell you that "oh, they stacked the box against us and had 8 and 9 guys in there and we can't block everybody". They beat 5 offensive lineman with 4 defensive lineman all day long. And they did it in every way possible. The beat both tackles with speed rushes to the outside. They consistently penetrated all the gaps in the interior and were either able to get to the quarterback or disrupt or stop the play of the running back. Many, many of the plays ended with all 4 defensive linemen in the backfield while atleast 2 or 3 of the offensive linemen were either on their back, fell down or out of the play. When running either outside or inside zone, they would fail to pass their lineman off to the next guy and nobody, all game long did anything to block the backside of the play, thus negating the boot plays that are a big staple of this offense. They missed blocks repeatedly, completely whiffing, and sometimes you saw 3 offensive lineman blocking 2 defensive lineman while the guy next to him runs by completely unblocked. There was zero movement of the line of scrimmage, nobody could sustain a block nor even appear to have the desire to, and our offensive line looked completely out-matched and out-muscled. Colby was beaten badly many times on the edge in his first start at tackle, and, I don't see where a lot of people think so highly of Richman because he wasn't any good either. Nobody could pass block, nobody could run block, and thus it made it really tough sledding for Petras because he got pressure everywhere.
Blocking
Not only is the offensive line blocking atrocious, but I think this is the weakest group of tight-ends with respect to blocking that I have seen. The wide receivers could not sustain their blocks at all either. There were so many running plays where if there was just one more block it would have put Williams in a 1-on-1 with some either a lineback or defensive back. I know it is not the pretty part of playing WR, but the big running plays come from downfield blocking.
Lack of downfield threat
We either have nobody on this team that can stretch the defense deep or the staff doesn't believe in anyone that can do it. Nobody even runs the routes. The route trees are awful and if anything it looks like many of the routes do nothing but bring defenders to the ball rather than get them away from it. Again, SDSU played us straight up. They rushed 4 down lineman, played 2 high safeties and sat on all the routes in front of them with the linebackers and corners. Sound familiar? Yeah, it should because it is how we beat teams all the time. And we obliged by running routes right in front of them, all day long.
WR play
WR play in general is awful. I get that Bruce is the best we have right now, however, his routes are not crisp to begin with. I don't think people understand how critical it is to run a crisp route. He seems to round all of his routes off (LaPorta does the same thing) and when a receiver rounds their routes off the defender can just run with them, thus you don't get any separation. I didn't see anyone run a hard-curl or even attempt a jab step to either side to get the defender on his heels which could get you a couple of steps. On the bubble screen Bruce just stopped and waiting for the ball and all that did is give the defenders time to blow the play up. We know from years of watching the bubble screen that the WR has to be running toward the ball, behind his blockers in order for this play to work. These little things don't seem like much but they are huge when it comes to getting open and giving your quarterback a larger window to throw. It is especially critical on those out-routes because breaking off the route too early and/or rounding it only brings the defender into the light of sight of the quarterback. Spencer really struggled with these throws, but, in his defense it is a difficult throw to make. But he should make it, granted.
As I stated earlier in the week, I think that Iowa was going to try to run their standard stuff on offense for many reasons: they didn't need to do anything exotic to win against an over-matched team, to establish the foundations of the running game and to simplify the gameplan. When none of that worked and your quarterback is off, it was better to just get out of there because there wasn't anything fixing it at that point. So I can see why he kept Petras in the game because there was no quarterback that was going to fix any of these problems, not yesterday during the game. I think a lot can be fixed, I think some can't, and I think that there is a youth and serious talent problem that will prevent this offense from being respectable. I hope I am wrong. But hey, we are 1-0!