Sean Manaea is in his 10th season in the majors and still was taken aback by the movement on Nolan McLean’s signature pitch in his MLB debut.

Making his big league debut, McLean shut out the Seattle Mariners over 5 1/3 innings on Saturday afternoon at Citi Field in a 3-1 win, navigating a deep lineup with an array of spinning breaking pitches. It was an impressive outing for the rookie right-hander, but when manager Carlos Mendoza went out to the mound in the sixth, fans booed the move.

Rookie Nolan McLean delivered what the Mets needed in his MLB debut, striking out eight and flashing some clutch leather over 5⅓ scoreless innings in a 3-1 win over the Mariners.