Found tweets of most of the deep plays. Here's the breakdown for each.
Play 1 (69 yarder): It's Cover 1 Man. Jamison is in man on the outside WR and does well until he quits on the play for no reason after he shoves the WR out of bounds. It's like he thought his man wasn't allowed to catch the ball after stepping out, which is not the rule. So a pretty big fuck up by Jamison. However, it should've been about a 35 yarder at that point. Schooler obviously fucks up majorly and gives up the remaining 30 yards. Since Schooler was in C1 and there was a deep route on the other side, you can't expect him to be there to break up the throw, but you can expect him to make the tackle. As for PK, he called C1 man on 3rd & 3. There's nothing unreasonable about the call.
Play 2: It' s a little hard to tell the coverage because the camera doesn't show it the whole time and I think it was busted by Jerrin Thompson. The outside CBs are clearly playing man and they're in a technique that indicates they think they have deep help. BJ Foster drops on the other side like it's C2. If it was C1, he should've been sprinting to the middle of the field at or before the snap. Jerrin kind of looks the same at first but then gets his eyes caught in the backfield and cheats up. I think he screwed up his responsibility and let the outside WR get past him without noticing. Jamison's coverage really wasn't bad and was actually probably about right if it was C2. There, you stick to your man but play his back hip so you can jump anything short/intermediate and you rely on the safety over top to help you deep. So if I'm right on the coverage, then Jerrin fucked up massively and no one else really made a mistake. If it was C1, then Jamison played the wrong technique and should have stayed over the top of his man way more. Same goes for PK. C2 man should be one of the least susceptible to a deep ball like that.
Play 3: Looks like we're playing Cover 3 based on how the top CB on the screen bails and Foster's positioning. It once again looks like a coverage bust. Josh Thompson should've had the deep third where the ball was thrown but instead was way too far up field because he was covering the outside WR at the bottom of the screen instead of trusting the play call and getting the proper depth in his zone. The offensive play is a C3 beater, and is designed to do exactly that to the outside CB. Get to bite on the outside WR, while the slot WR runs up the seam then fades to the outside so the middle safety in C3 can't get to it. Problem is, you would expect your 5th year CB to not get caught by that...unless he spent most of his career being coached by Todd Orlando. Josh Thompson screwed up massively. I'd say BJ Foster screwed up some because there was no other route to hold him middle, so he should've been faster in getting over there, even if the play ended up outside his zone. Problem is, Foster is not a rangy deep safety so he's susceptible to stuff like this. Once again for PK, he called C3 on 1st&10. Nothing really wrong with that. He didn't go full Todd Orlando and call Cover 0 on first down.
So overall, I'd say there wasn't anything wrong with the scheme. We had 3 coverage busts by 3 different guys. Problem is, the coverage busts are so wide spread and there were so many that you can't reasonably write it off as a one-time thing. Our senior CBs are not playing to the level you want and they've been space cadets for years now so not a ton of reason for optimism. I'd like to see more of Dunn. He may have the same flaws, but we haven't seen them yet and he's looked pretty good when he plays. Safety is a problem. Schooler has been pretty bad at everything. Same for Foster. I'd say Jerrin Thompson is our best safety so far, but he's messed up a good bit too. It's a little like the OL. It's disappointing that our secondary is this bad and making these kinds of mistakes, but our players have received shit for coaching most of their careers, so the litmus test for this coaching staff will be how much we can improve over the course of the season.