Arena Mode Matchmaking Issue

As frustrating as this may seem, Unfortunately this is actually beyond the devs to fix. 

Squad and fleet arena are not one pool with all the people of the game. When you unlock the arena you are put into a "Shard" with other accounts. You cannot leave whatever shard you are put in, so If you had taken a break from the game you are unfortunately stuck here. As the people you are being matched up with are real people, They most likely set their best team on defense to drop as little as possible, and there is little CG can do to change it because the goal of these game modes are to have as high of a rank as you can.

As for "Cannot Win", That is a different story. the Team Power rating has nothing to do with how strong or effective your team is, And is mostly a cosmetic number unless you are coordinating with your Guild in Territory Wars so paper teams don't get placed on defense. What matters more is the units on your team. For instance, the "Grim Reaper" player you see in all three screenshots (Which is because that player is the highest you can increase rank in one attack) has a Galactic Legend. If you do not have a Galactic Legend and their proper team you should not expect to win the match, And even then there are GLs that would lose against other GLs (For instance, Supreme Leader Kylo Ren would most likely lose against Reaper's Jedi Master Luke)  For other matchups, It is a lot like an advanced game of rock / paper / scissors. Some teams can walk over a team while others get shut down. For Example, if you are running a team like "Zach Bostater"'s Jedi, It would not be a good idea to attempt to beat "ZockEnderLP"'s Sith Empire team, As that Sith Empire team is meant to beat (non-GL) Jedi teams. Unfortunately without Galactic Legends (Which it appears you do not have) There is no universal team that truly beats everything, esp. if you are trying to beat Galactic Legends without one yourself.

When building teams, Try to make teams that fit together well, and usually the best teams almost always involve the journey guide in some way. If you need a team recommendation, I would recommend Commander Luke Skywalker (Lead, Journey Guide), Han Solo (Raid Currency), Chewbacca (Journey Guide), C3P0 (Journey Guide), And Threepio & Chewie (Light Side 7-A (Hard)), as that is an excellent team to help you until you obtain stronger teams such as Galactic Legends.