When I'm reading letters, I've noticed that I do pay attention when writers bold or underline or italicize material to add emphasis, so that's okay to do.
Since there are no commas before and after the italicized clause, the italicized clause is restrictive and suggests that only those athletes who perform exceptionally are entitled to such salaries.
Never cross an I, unless it’s by itself, always italicize and bold for emphasis — and all of them were made to make comics printed on bad paper easier to read.
Note to Instructor: In the following exercises, allow the student to look at the list of synonyms given as he repeats the sentence three times, substituting different synonyms for the italicized word you emphasize.