The drainage is not bad I think, it's a raised bed mostly organic matter although the subsoil is clay, and for sure it was a very wet year.
I don't think the soil is that great either, it was the best spot I could find that had no alliums the year before. A bit shaded too. Peppers did well there because it's sheltered on the north. I meant to cut some trees that are partly shading that bed but didn't get to it this spring. So it wasn't optimal in several ways.
I didn't know that about the purple stripes sizing up at the end, but I think you're right it was too early to harvest them, their scapes were a good bit later than the Music. So the small size can't really be blamed on a virus. It's my fault for panicking and pulling them all up.
I have a few plants of Persian Star that are in a different bed, and just put up scapes a couple days ago! So late.
They look healthy enough, so perhaps they'll have a chance to size up before the season is over.. I read somewhere that garlic should be ready about 20 days after their scapes are cut.... ? Lots of wild guessing here.