McKay's four homers matched the Louisville record set by Jim LaFountain on April 24, 1976, and he's the only NCAA Division I player to accomplish the feat this season.
McKay's first home run of the game, a two-run shot to right-center field in the top of the first inning, started the scoring for Louisville, and he tacked on a second two-run homer in the following frame, extending the Cardinals' lead to 7-0.
A two-out error by Eastern Kentucky's third baseman enabled McKay to bat in the fourth inning, and the 6-foot-2, 212-pounder capitalized on the opportunity, belting a three-run homer over the center-field wall for his third home run in as many at-bats.
McKay was called out on strikes in the seventh inning, his lone out in the game, before making history in the ninth, when he deposited a 1-0 offering beyond the wall in right-center for his third two-run homer of the contest.
McKay, 21, won the John Olerud Award as college baseball's best two-way player -- he plays first base when he's not pitching -- in each of his first two seasons at Louisville after turning down the Padres as a 34th-round pick out of high school.
He's a lock to win the award again after dominating more than ever this spring. Through 39 games, McKay is hitting .405 with 11 home runs and 39 RBIs.
On the mound, McKay has been his usual dominant self, going 6-3 with a 1.83 ERA in nine starts for the Cardinals. He's allowed just 37 hits, including 11 extra-base hits, while compiling 83 strikeouts and 15 walks in 59 innings.
For his career, McKay is 26-10 with a 2.00 ERA and 328 strikeouts in 265 1/3 innings spanning 46 appearances (39 starts).
That McKay is in the mix for the No. 1 overall pick this June is testimony to what scouts view as legitimate potential on either side of the ball. He's expected to be selected inside the first 10 picks either way, though performances like the one he had Tuesday certainly won't make the decision any easier.