This is quarters coverage, so he is playing down hill against the run. When it's determined it's a pass he will help bracket WR on that side. He has no responsibility to help on routes on the other side of the field.
Peel, who is the guy who ultimately got beat is the player in conflict. Generally quarters rules are anything over that 8-10 yard threshold is who you're taking. The play is great design because they run a square in right at that 8-10 yard mark to occupy his eyes and run a post right behind him. Where the defense fell apart is in both cases you can see the slot defenders opening up their hips with outside leverage, meaning they were expecting inside help. The fact that they're playing the WR like they have inside help, and ultimately don't, is a problem.
Edit, Sterling not Peel
This is correct all except the boundary safety not having pass responsibilities on the other side and him being a bracket player.
He is a fast flow alley player whether that fast flow is run or pass, the alley is his coverage.
The safeties in quarters coverage are both run/pass players and they read the last man on the line of scrimmage for high hat or low hat from that guy.
If they get fast flow away, they roll to the top, and in essence the coverage becomes a post inverted cover 3.
Meaning, after play side safety drives on the fast flow to his side, backside safety rolls to the top, it, and, in essence, it has become a cover 3 at that point. The post inverted just simply means you have inverted from 4 to 3 post snap.
If they get high hat they drop to pass, and if they get low hat they fit on the run.
Baylor set us up
In the 1st half OSU was rolling that boundary safety over the top because they were driving the overhang player, Sterling, on the settle route.
Again, that rolled coverage is just a post inverted Cover 3. Cover 3 is usually just a post invert off of Cover 4 so they work well together.
Well, then, since we were rolling the safety from the single side, Baylor then scrambled back to the boundary, then then ran a rail to the back to that side and also threw a slant back that way.
So.... OSU had to stop rolling that safety over the top because they were beating us on it.
So.... because Baylor had attacked the single side, OSU had no way to post invert to cover 3 and roll the single side safety.
But, yet, we stayed in quarters coverage against that 3x1.
So.... Knowing that we were no longer able to roll that single side safety, Baylor then could get to the front side prongs to that play.
Bernard apparently wasn't aware that we could no longer post invert the single side safety, or he must have thought he was going to have a drop from Sterling.
Apparently Sterling didn't know we couldn't post invert either and drove on the settle route.
So... we had no backside safety help, no front side safety help, and a corner who thought he was going to have help from one or quite possibly both of them.
It's just typical of how other teams set us up, adjust to how we line down and cover, and how we have no answers when the other teams has different prongs to the play.
We stayed in quarters coverage knowing we had no way to post invert a backside safety. Thus, we had no way to cover any kind of option concept where the qb reads an overhang player and has an either or decision as to who to throw it to.
These type of errors are why we rush 3, which means you don't get pressure on the qb, then at the same time there are receivers running wide open.
It's totally inept!
This is exactly why many of us knew as soon as we hired Knowles and his quarters defense, that there is no way it would work against these multi pronged offenses of the Big 12.