I have a small plot of barley/whet (not sure what it is) and i've noticed that the ripening of the heads was quite inconsistent. Some tillers where at hard dough stage while other tillers of the same plant are just emerging their heads. This wasn't here before.
Sorry for the late reply- I hope this is helpful to you still.
A lot of small grains seem to ripen at uneven rates. Commercial growers often spray grains with something to make sure the plants are all dead and at the same dryness before harvesting.
Uneven ripening is why using a shock or stook is helpful, so that all the grain heads can be protected from shatter and the elements while they reach the same level of dryness.
Here's a picture of some spring wheat I grew a few years ago, zoomed in. This field was definitely ripe for harvesting, but you can still see how some heads were green and others were golden brown.
Sometimes, though, this can be an indication of disease. This particular crop was afflicted with fusarium blight, of which one of the symptoms is some stalks of grain die a lot earlier than others which aren't ripe yet. I don't know if that's what's causing your uneven ripening, if you don't see any signs of plant disease it's probably just the natural unevenness of the process.
I'm sure glad that he's gone. Now I can read this tiny ad in peace!