I was also most unpleasantly surprised to see that not a single new swarmer card was made when oppression was released.
My current swarmer deck warpath/verore/verore does decently well so I dont think swarmers are a "joke deck" although maybe im still playing against non-metas/etc.
Broodlord, itself, is a piece of trash. Nobody can deny this. It's what swarmer decks NEED but the drawbacks are much to severe. It NEEDS to allow ability cards. Without it, swarmers have no way of winning. You can only body block so much before you have an empty hand.
Blazing Swamers need a swarmer version of "gather the weak" to even make blazing worth considering. FD doesn't offer enough options over factions offer to justify using it.
Tranquil Swarmer is also a joke with its ability only reducing morale loss by 1. It should've given swarmers vigilance like Blazing gives haste.
Warped swarmer before nerf was great. Now, its still decent, especially if you can get all 3 out.
Brutal swarmer is staple because its the only one that gives a decent buff. Also, caretaker is warpath, which is also staple.
Consuming Swarmer is decent. Buffs our bugs for each kill it gets. Sadly consume 2 doesn't stack like Brutal's buff but I can see why it cant. Imaging consume 6! +6/+6 per kill PLUS heals 6.
Artificial Swarmer is also okay. Gives a lower +1/+1 but also makes the bugs artificial allowing for easier buffs from Genesis cards. But unless you build mainly GI over WP, its not that great.
Ascending Swarmer, I don't know. Never used but the fact that it exhausts both itself AND its target makes it a bit too slow. I could be wrong though. Maybe if you used with Artifical to make them flying and overbuff them via secluded constructor...
Infected Swarmer is good with its infect BUT sleepers are getting rotated out, meaning its going ot obsolete soon.
Overall, I think Swarmers would be High B tier in terms of strength. Not joke level tier but not good enough to win against a majority of the meta decks. Which is where swarmers should be. Just that it needs to get new cards to compete with the other decks as new sets are released or else it'll fall into oblivion.
Pretty much, if a new swarmer ISN'T released when the next faction is released, then Swarmers are offically left for dead and abandoned.