I cant dl the newest version of the game, so I cannot watch the replay again, but there are 2 kind of even encounters around the midway. First is the one where your opponent chases you with scorchers, those die, then goes in with the ravagers. And then there is the one I assume you mean, which is where it looks like you would lose. What confuses me is that the first of those 2 encounters works quite well for you, the second maybe not. The thing is that you abort the figt the moment the ravagers are completely slowed, which should shift the balance into your favor quite a lot.
But then, the most important thing is that you do not fight with your entire army. Ravagers can shoot over each other, thugs cant really. So you are effectively fighting the whole ball with the damage output of 3 or maybe 4 thugs. What you do is using a defensive formation that puts the emphasis on the shield-link, not damage. At least in the past, ravagers used to be not that good against shields because they didn`t have the fire-rate and damage to go through the shields well. Maybe the nerfed shield-regen is a thing as well? Not sure. What I think needed to be done is a bit more spreading to allow all of your thugs to fire and profit from the full slow. You could also do a bit of rotation, pull the damaged thugs back behind the fresher shields of their comrades.
(On a sidenote, I do not understand why you insist on building felons. Assaults are kind of a counter to them, and their shield-drain somewhat works against the defensive formation. But that is probably not of any concern for our actual topic.)
Now again, I cannot log in to do my own tests, and I might be quite wrong. This post is not me saying I am definitely right and you just cannot play shields well. I will look at it again as soon as i am able to log in.
Skuttle might work well, but if you say that ravagers can go around a shieldball simply, then I would argue that skuttles are really slow and the ravager-player can screen with darts. It should be comparatively easy to avoid getting skuttled. Maybe. BUT if you have a jumpy fac already, why not go for placeholder? THAT should allow you to use almost anything INCLUDING skuttle to finish your opponent off.