LOS ANGELES — As a wide-eyed 23-year-old who took Major League Baseball by storm last summer, Jacob Misiorowski seemed in awe of his circumstances. In his big-league debut against the Cardinals last June, the Missouri native watched Nolan Arenado step to the plate against him and almost couldn’t believe it, though Misiorowski did not let his new reality overwhelm him. He threw five scoreless innings in his first MLB start and was named an All-Star just five appearances into his big-league career, to the excitement of some and the indignation of others. The wonderstruck rookie looked spellbound...