After five season in the Mets' minor league system, he made it to the big league club out of Spring training in . In the second game of the season against the Montreal Expos, Cornejo entered the game in the eighth inning with the Expos leading 5–2, and pitched the final two innings without giving up a run.
Cornejo's ascent through the Mets' minor league system took five seasons before he reached the major leagues via Spring training. In his second contest of the season against the Montreal Expos, Cornejo entered the game in the eighth inning with the Expos holding a 5–2 advantage and successfully completed the final two innings without yielding a run.