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.)