Brandon Relf reached on an error by ASU third baseman Raoul Torrez to start the game and then proceeded to steal second base. After getting a strikeout, Kelly then gave up a base hit to Alex Wolfe, but Marrero gunned out Relf at the plate on a relay throw from center fielder Andrew Aplin.
That didn't work Kelly off the hook, because Bryce Ayoso then singled sending Wolfe to third and then a balk was called on Kelly, allowing Ayoso to score.
ASU (41-5) evened the score in the third inning, getting an unearned run of their own. Aplin reached second on a throwing error to start the inning, moved up to third on a groundout and scored on an infield single by Drew Maggi.
An RBI single by Raoul Torrez put ASU in front 2-1 in the fourth and then Marrero struck for his fourth home run of the season to put the Sun Devils up 4-1.
BYU (20-27) got another unearned run in the fifth inning, this time off of Jake Borup. Austin Hall reached on a bunt single to start the inning and Austin Barnes threw the ball away, allowing Hall to advance to second. Hall then was sacrificed up to third and scored on a groundout by Relf.
Riccio Torrez scored on a throwing error in the sixth inning and Marrero capped the ASU scoring with a two-run triple in the eighth.
Kelly and Borup each worked three innings and allowed one run, but it was unearned. Borup worked around five hits and picked up his 10th win of the season.
For the second straight night, Mitchell Lambson, Jake Barrett and Jordan Swagerty each worked a scoreless inning of relief.
Marrero and Raoul Torrez each finished 2-4, while Johnny Ruettiger continued his hot streak by going 2-3.
On Monday, Ruettiger blasted two home runs to lead ASU to a 14-0 drubbing of the Cougars. Seth Blair and Brady Rodgers each worked three scoreless innings on Monday.
The victory on Monday was the 40th of the season for the Sun Devils, giving ASU four straight seasons and the 31st in program history of 40 or more wins.
The Sun Devils will return to Pac-10 play on Saturday when they open up a three-game series in Tucson against UA. First pitch on Saturday at Sancet Stadium is at 6PM.