I think it might be useful to come up with a list of competent players, because most of the characters are total idiots.
LittleFinger - Other than pissing off Sansa, I can't find a lot of fault with anything he has done. He controls the one fresh army left in Westeros.
Tyrion - maybe competent. Went from being the most wanted man in Westeros to being the Mother of Dragon's Consigliere, but the deal with the Slavers seems like a bad idea, and he did get all his ships burned. He has also pissed off Missandei and Grey Worm. He will have to raise his game when the Iron Islanders show up.
Queen of Thornes - We are probably giving her more credit than she deserves. She let her heirs get captured by fanatics, Cersei has been holding her own against QoT for the whole season, and the QoT is stuck in an alliance with a family she hates while the rest of Westeros lights itself on fire again.
Dany - I have a suspicion that Dothrakis on boats is going to turn into a disaster somehow.
High Sparrow - playing with fire. He needs to release the prisoners to finish his takeover, but he is in danger now that they are no longer prisoners. Still, he is playing the game very well so far.
Yara - She got the upper hand on her uncle, that's for sure. That said, Iron Islanders don't have a great track record of actually winning anything. It would be more interesting if her and Theon get to Dany before her uncle.
Blackfish - Got a castle, an army and some allies. Also has the chance to get rid of his idiot nephew. We will see about the siege next week. If he is smart, he will stay in Riverrun.
Margaery/Tommen - Tommen is alive until Margaery decides she doesn't need him anymore.
Bran - If Meera was smart, she would find another man. In 5.5 seasons, Bran has only outsmarted Theon. Not a lot of great pelts on the wall.
Incompetent:
Sansa/Jon - The writers are going to have to stretch credibility to keep these two morons alive.
Arya - Jaqen and the Waif were probably the two worst people in the entire world to piss off. Literally #1 and #2 in that order.
Cersei/Jaime - Incompetence, thy name is Lannister. I assume that Jaime and Brienne are going to run into each other in the Riverlands. This is Jaime's last chance, because Cersei is going down hard if the rumors of a Second Battle of Blackwater are true.
Dornish Idiots - I wonder if we are done with these morons.
Euron - It is not good for any character when Theon gets the best of you.
Ned Stark - An idiot even from the grave. I was watching the fight against Sword of the Morning again this weekend. Ned shows up at a small castle in the middle of nowhere with 4 of his buddies against 2 Kingsguard (3 in the book), and rather than working out a peaceful solution, Ned lectures them on their duty until a fight breaks out and 3 of his buddies and the greatest swordsmen in Westeros get killed.