5.

How do stanzas 12-13 contribute to the theme of the poem?

There is no passage and answer choices, so it is impossible to answer this question. I apologise.

The description of Casey's changed attitude continues at the beginning of stanza 12. That "smile of Christian charity". Now his "teeth are clinched in hate." Casey has gone from a dependable, athlete, to the disparity of the team's success. The lines, "Oh, somewhere in this favoured land the sun is shining bright, / The band is playing somewhere, and somewhere hearts are light; / And somewhere men are laughing, and somewhere children shout, / But there is no joy in Mudville-mighty Casey has struck out." have a contrast between the shining sun and laughter, to Casey striking 3 balls out. The stanzas contribute to the theme that too much pride can lead to failure, or that one shouldn't depend on overconfidence.