I don't see many works whose major failure lies in a break down in theme, but it can be done.
Take the second and third Pirates of the Caribbean flicks. The first one ran changes on the notion of a pirate, and a good man, about moral ambiguity in the face of complicated situations. The second two? What are they about? We have the scene where the governor is told that loyalty is no longer the coin of the realm -- coin is. But does anyone act out the role of loyalty? The entire movies are morasses of unreliability in characters, and Jack Sparrow justly argues that the pirates can not hole up against the fleet because they will tear each other to pieces. A flat static idea like that can be setting, but not theme. The only truly contrasting thematic elements were the romances between Will and Elizabeth, and Davy Jones and Tia Dalma. From the way Will watched them when they were prisoner, I suspect he asked Elizabeth to marry him while they were fighting so that if only one survived, the survivor would have the consolation of knowing that they had patched up their differences, which covers two ways of dealing with love after betrayal.
Echoing subplots are the commonest way to underscore theme, since they can ring changes on it, but if there is no echo, it will not produce the effect. And that can be a real danger in action and adventure, where you keep throwing things at the characters to keep them on their toes, that they aren't orchestrated in a manner that fits together.
I was thinking of this in Ordeal In Otherwhere. Charis is desperate in the opening because she has fallen; she was the beloved and well-educated daughter of government teacher, but on the colony Demeter, a mysterious plague with a strange affinity for men and older boys among those who favored the government let loose a strain of fanaticism in the colony, and she signs the indefinite term labor contract to escape. Then she arrives on Warlock, where there are troubles because only the female Wyverns dream, and they subordinate the males because of it, and when a human company brings in a machine that lets the males escape the females' mental powers, trouble ensues. BUT -- to "dream" means to be able to recognize an illusion while you are in it. Shann Lantee, a human male, was acceptable to them because they were unable to trap him with either fear or longing for something lost. This is a highly desirable trait in those in charge. Nowhere does Charis even think to compare the mind set of the Demeter colonists with the inability to think your way free. To be sure, it would have slowed down the action, and perhaps made the problem irresolvable, and I missed it entirely, reading it while I was younger, but now it strikes me the lack of connection.