In "Casey at the Bat," the poet Ernest Lawrence Thayer uses a number of different types of figurative language and poetic devices. Here are some examples.
1) Alliteration: the repetition of initial consonant sounds
a) "A sickly silence"
b) "deep despair"
c) "the former was a lulu and the latter a cake"
2) Assonance: the repetition of initial vowel sounds
a) "if only Casey could but get a whack at that"
b) "Flynn preceded Casey, as did also Jimmy Blake"
3) Metaphor: a comparison that does not use the word "like"
a) "Cooney died at first" (Cooney did not actually die; his
being thrown out at first base is compared to dying.
4) Hyperbole: exaggeration
a) "Blake...tore the cover off the ball." It is quite unlikely thatBlake literally "tore the cover off the ball." This is merely an exaggerated way of saying that he hit the ball very hard.
5) Simile: a comparison that uses the word "like" or "as"
a) "From the benches...there went up a muffled roar / Like the beating of the storm-waves on a stern and distant shore."
(This could also be considered an example of hyperbole; see above.)
The famous poem "Casey at the Bat" is full of figurative language, as the other educator has pointed out. Let's take a look at a few more examples:
Personification is the attribution of human-like qualities to non-human entities or inanimate objects. We see personification in the seventh stanza of the poem:
Five thousand tongues applauded when he wiped them on his shirt...
Tongues are being personified and provided with a human action that they cannot actually perform. This figurative language implies that people are shouting joyously as Casey prepares to hit the ball.
Hyperbole is the use of exaggeration to convey an emotional point. We see hyperbole used in the tenth stanza:
With a smile of Christian charity great Casey's visage shone...
The implication that Casey's grace in this moment is "Christian" portrays him as saintlike when he has, in reality, not yet hit the ball. It conveys the sense of worship that the crowd has for him and the composure that he has while playing.
We see this same technique used two stanzas later, when Casey takes his final swing:
And now the air is shattered by the force of Casey's blow...
Obviously air does not actually "shatter"; this word was chosen to place emphasis on the deeply disappointing fact that Casey has missed his final shot and let down the entire crowd. This creates a moment of unbearable tension as we realize that Casey--who has been built up as a hero of baseball for the entirety of the poem--has failed to perform the way we expected him to.