Oh, that's your problem?
Yeah, that's a problem with the matching algorithm that bases matches on toon's using the old power rating system. The matching algorithm doesn't use Galactic Power, but instead uses the original Power stat. That power stat did not consider things like Ability Level, so a toon with a level 1 leadership and a toon with a Zeta'd leadership have exactly the same power as far as the matching algorithm is concerned. The MA also doesn't consider mods directly (it considers your health, and if your health is changed by your mods it does consider that). It also severely undervalues Speed. So you can increase your speed a ton and have your matches barely change, if at all. Zeta/no-zeta does not change matching.
So ... this is more about you just getting hosed by EA. I'd still pre-load TM, because a suicide squad that can take out Baze will be useful, and if you have an Annihilate saved up, then you have a good chance to take down CLS. But that's dependent on not having a taunter in there, which means you need someone to stun or dispel Baze and then a bunch of damage dealers to take Baze down.
Preload TM on Rebels + Boba. Hopefully the rebels will do more damage than Baze can heal, but once protection is gone they won't do a lot directly to Baze's health because your crits will be giving Baze HoTs. After a bunch of rebel attacks go off, Boba goes and uses Execute, with the many HoTs super-powering his damage as they are dispelled.
Then, if they die fast enough, Baze won't get healed up again, or might even be dead. Your sith come in, clear the remains of Baze if they have to, and nihilism gets rid of CLS. Hopefully your Sith can also take out one other toon, any of them are good choices. You won't have to worry about GK's auto taunt because your sith can't do crits, so if Baze is down and CLS gets annihilated, taking down one more should be possible.
Whichever 2 are left will still be tough nuts to crack, but that's the job of your 3rd squad, whoever they are.
I'm not saying this will always work, but it's the best strategy you're likely to get against a really unfair EA algorithm. I have my own problems with a team they keep feeding me on g12: zQGJ (L), zBarriss, GK, zzYoda, Aayla. I never picked up Nihilus, so my best damage dealers all deal Crits, which activates GK, who heals 20% health ever time you crit against him and had a huge health pool. Leia against GK with zBarriss just heals him like a Ring of Regeneration.
I decided a while ago to put together a resistance team, and I've got all of them at 7* except finn (6*) and almost all at g9 (RT & R2 need Mk3 Holos). Got 17 zeta mats. Hopefully when they've got TM preloaded and expose does as much damage as Barriss heals (and they don't do as many crits anyway, I can use them to rip through GK and either QGJ or zBarriss, taking protection off some others. I'm worried about Yoda, but we'll see how it goes. In any case, if I can get rid of either QGJ lead effects or Barriss' frustrating insta-heal, then my crit dealers can come in and mop up.