First, if you read this article you might get some other ideas that will help you. The basic ideas are to try to keep water out to start with but if it gets in, try to get it out. When the weather sets in wet, that can be next to impossible, especially if you have a run of any size.
Pat’s Big Ol' Mud Page (fixing muddy runs):
https://www.backyardchickens.com/web/viewblog.php?id=1642-fix-a-muddy-run
Those concrete blocks may be a temporary solution, but how will you like them when it dries out? I’m not sure you’d be happy with them long term. Maybe create a walkway with them, more for you than the chickens, but consider some other ideas for the long term.
I don’t know how big yours is or your circumstances, but can you put in a berm or swale above it to divert rainwater run-off? Does the roof of your coop slope so the water runs into the run? Maybe a gutter to divert that.
Again I don’t know how big your run is or how steep it is, but could you stack those blocks along the bottom and backfill with sand? Sand drains really well but it needs somewhere to drain to. Sand will wash away in a heavy rain. Chickens will scratch it and throw it all over the place, including out of the run. A stack of those blocks along the bottom will help contain the sand yet water will be able to drain out as long as you don’t mortar them. Filling your ditch with gravel sort of like a French drain can get rid of a lot of water too. And use coarse sand, not the real fine play sand. Coarse sand will last longer. They’ll use it for grit too.
The sand will eventually disappear, either washed or scratched out of the run or more likely sink down into the mud. Gravity causes that. Once it dries out a layer of rock or gravel underneath will help with that, but that may be a dry weather project. If you do use rock, I suggest round gravel like pea gravel or stuff from a creek or river bed that has been rounded off so the chickens don’t cut their feet when scratching.
