Since Meereen the genius of the Lannister family and possibly the smartest person in the seven kingdoms has been slipping. He made a bad deal with the slavers in Meeren that totally backfired on him, and was not solved until Daenerys is able to clean it up by incinerating the slavers while making use of her brand new Dothraki horde.
Nevertheless, Tyrion agrees with Daenerys to make an alliance with Yara Greyjoy in return for their ships. Tyrion is not a fan of the Greyjoys after previous moves have shown them to be weak and disloyal. Smart move as working with Euron Greyjoy is not a great choice — because he’s an asshole. Creating allies makes sense.
When he is making war plans with the leaders of the different houses (Ellaria Sand, Olenna Tyrell, Yara Greyjoy, et al), he points out that their plan is to lead the seven kingdoms into peace. In order to do so, they need the Dornish army and others to be able to fight Cersei’s army, while the Unsullied take Casterly Rock. (Note: If I’m messing anything up, let me know).
Here we are an episode later, and Daenery’s has lost her fleet of ships from the Dornish and Iron Islands as they have been torched by Euron. Euron has taken Yara captive, and gave Ellaria Sand to Cersei, who has since poisoned her daughter. After attacking and capturing Casterly Rock, Greyworm and the Unsullied look beyond back to the ocean to see that their ships have been burned by Euron’s fleet, and they’re essentially stuck. An entire army is now land-locked.
Jaime and the Lannister army have conquered Highgarden while being led by Randyll Tarly and Bronn. When talking with Olenna, Jaime remarks that his father always used to call him a “slow-learner”, and in my opinion this is the difference between Jaime and Tyrion. Tyrion’s focus is on creating the perfect plan in order to execute Daenerys’ vision of eventual peace and being Queen of the seven kingdoms. Jaime and Cersei are playing to win. Cersei is the same woman that blew up the Great Sept of Baelor, leading to the death of many, as well as her own son’s suicide, and ending with her becoming Queen of the Andals (seven kingdoms, kinda). After becoming Queen, Cersei was now more open and ballsy than ever. She goes: “Yeah, I fuck my brother, who gives a shit, I’m the Queen, if you care, you’re dead.”
It’s almost as if the tables have turned. Tyrion’s whole life has been having to prove himself when push came to shove. Now that he is being respected and given power, his focus is on not making the dumb move, while when under pressure he would use his ingenuity to find the way to yield the outcome he wanted. Cersei and Jaime are winning because they know that they have nothing to lose. Their father is dead and their mines are dry, losing the Rock is not a big deal as the Rock was only a symbol of their father — who is dead and they hated.
I do believe that Tyrion will pull through in the end, the only problem is that they will need to get blood on their hands to win and claim the seven kingdoms in the name of Daenerys. He does his best work when pushed up against a wall, not as a politician.