His major league debut, against the Houston Astros, went poorly; making the start, he retired just one of seven batters, and was pulled with four runs already scored, and runners on first and second.

The Mets had pushed a run across, and had runners on first and third when Berenyi exited the game in favor of Tom Hume.

[3] Young starters Berenyi, Soto, Frank Pastore and Mike LaCoss, behind veteran future Hall of Famer Tom Seaver, pitched the 1981 Reds to a Major League Baseball-best 66–41 record.

However, due to a split-season format, caused by the 1981 Major League Baseball strike, the Reds finished in second both halves of the season and thus failed to make the playoffs.

[11] He was 3–7 with an even 6.00 ERA on June 15 when the Reds traded him to the Mets for minor leaguers Jay Tibbs, Eddie Williams and Matt Bullinger.

Due to their core of young prospects, the perennial cellar-dwelling Mets were a surprising 33-25 when Berenyi joined them.

[12] He lost his first Mets start,[13] but rebounded in his second, pitching seven shutout innings against the Expos before handing the ball to Doug Sisk.

He signed as a free agent with the Expos prior to Spring training 1987,[18] but failed to make the club.