Carvell ran really strongly for a 19 year old with limited experience (think he was third best on leg 1) and has a recent pb only a little faster. 1st leg is by far the hardest. Something went wrong on the first changeover and that put the rest well out of it. It's a disappointing mistake but better here than in the Olympics and hopefully lessons will be learnt.
MHS is not a natural relay runner in the sense that he clearly struggles with his race management in relays (it's taken him a long time and a hell of an effort to become the individual 400 runner he now is despite huge talent as a junior runner) and so has ended up doing the first leg solidly but unspectacularly. He clearly, and quite sensibly, prioritises his individual race. I don't expect to see him in the mixed in Paris. This year is his chance to win individual Olympic gold (not saying he's favourite) and I don't think he'll jeopardise that even for the chance of relay gold.
Dobson is fragile physically and so races sparingly which is smart. I imagine we'll see him and Hudson Smith in the men's relay in Paris when they've done their individuals. If CD is feeling strong come Paris and with the hope of more Olympics ahead of him, he might do all 3 events.
The really promising thing is that seven of the top eight men in the UK have run PBs this year. That's really unusual and encouraging.
The situation for the women is more complicated.
Everybody understands that Amber Anning has only limited availability and her season may be mostly run by the Olympics. If you look at how Adeleke and many others have run at international championships after competing in the NCAAs then it does not indicate that Anning will be at her best. We can hope, and some athletes buck the trend but my guess is she'll be somewhere between 0.5 and a second slower than whatever she runs in the NCAA final. Her uni paid for her training so it's fair enough.
The rest of the women are of a remarkably similar and decent standard and I think most of them know that when it comes to Paris, they are relay runners who might get a run in the individual. However, because they are so similar, it is important that they focus individually now in the run-up to British championships so the selectors can fairly and objectively identify the top six and in what order. Keely being in the top 5 is purely a function of her being amazing and, in my view, in no way an indictment of the rest.