When Carson Whisenhunt, Carson Seymour and Carson Ragsdale were all in the same Triple-A rotation, they invented a little game. The three often would walk around the ballpark together, and if a fan yelled out “Carson” the first one to turn around would have to go and sign autographs.

SAN FRANCISCO — With the Giants’ rotation in flux following Hayden Birdsong’s demotion and Landen Roupp’s injury, manager Bob Melvin announced following Sunday’s 5-3 loss to the New York Mets that top pitching prospect Carson Whisenhunt will start on Monday and make his major-league debut.