The arugula seems to be growing OK, but many of the cole plants have these little, thread-like stems. These two look like they've been nibbled:

and

but this one _doesn't_ look chomped, but it's still too thin to hold the plant upright. It's growing, but it's kinda laying down on its side:

and

They were all kinda spindly when I thinned them, and then they just got worse.
I started them in partial sun, then moved them to full sun for 2-3 days before I transplanted. I have them under a lightweight row cover (allegedly 85% light transmission) to prevent the peafowl eating them, but I still have bugs under there (see last photo).
Did I transplant them too early? Too late? I had little white rootlets coming out the peat cups, so I figured they were ready to go.