Switch out Sion for Grand Moff Tarkin (at least until they fix his zeta).
With Grand moff dropping crit chance down and offense down, not only does he make your opponents hits very weak, he is also speeding up your whole team like mad because of all the tm gain from the palps lead and his debuffs. Not only that, but he's reducing the enemy's tm all the time. It gives you complete turn superiority.
Vader going first and dropping force crush makes your whole team go next. It can't be countered, so always do this. Don't fracture with Thrawn turn 1 have him swap to someone else.