JJ Picollo glanced at a copy of Sports Illustrated from last May, a glossy reminder of the attrition a major-league season exacts on a pitching staff. The five members of the St. Louis Cardinals starting rotation smiled back at him. The magazine extolled the quintet as the team’s backbone. Except when the playoffs began four months later, sixty percent of the group had left the rotation, replaced by a collection of youthful reinforcements like 22-year-old Michael Wacha. The cover caught the eye of Picollo, the Royals’ assistant general manager, recently as he relayed his organization’s plan for 22-year-old Kyle Zimmer, the No. 5 pick in the 2012 draft and perhaps the finest prospect in their farm system. The Royals do not expect Zimmer to contribute to the club this April. But their expectations for him as the season progresses are sizable. “The goal would be to have him peaking in the minor leagues in late May, June, going into July,” Picollo said in a telephone interview. “And then really ramping it up and taking the handcuffs off him, hopefully in a playoff run, and he pitches in September and hopefully October.” A bout of biceps tendinitis shortened Zimmer’s full-season debut in 2013 to only 108 1/3 innings, but his ceiling has not lowered. During the winter, he received plaudits from the baseball-prospect hype machine: MLB.com designated him the No. 30 prospect in the game, and Baseball Prospectus rated him No. 41. Baseball America placed him at the top of the organization’s list, ahead of fellow right-hander Yordano Ventura. Scouts project Zimmer as future stalwart with the bullying fastball and bending curve of a legitimate No. 2 starter. As a pitcher, Zimmer is a relative neophyte. He converted from third base in college. Since the switch, he has dealt with hamstring and groin issues, in addition to bone spurs in his elbow. The Royals hope his nagging injuries cease as he acclimates to the pace of professional baseball. The trick for the team is protecting his right arm while capitalizing on its value. Picollo portrayed 2014 as the first half of a two-year plan designed to legitimize Zimmer as a full-fledged rotation member for 2015. He received an invitation to big-league camp, which opens next Friday in Surprise, Ariz., but his stay in the Cactus League may be brief and his presence in the fifth-starter competition is perfunctory. As an organization, the Royals like to limit their pitching prospects to 20-percent workload increases per season. Picollo indicated Zimmer could exceed that threshold slightly. If he throws 150 innings, “we’ll look at that as a successful year for him,” Picollo said. “We’re going to be real slow out of the gate with him,” he added. The arrival of Bruce Chen created a logjam for the final spot. Ventura and fellow top prospect Danny Duffy will compete. General manager Dayton Moore listed Luke Hochevar, Wade Davis and Chris Dwyer as additional candidates. The team also inked to a minor-league deal Brad Penny, a two-time former All-Star who hasn’t started a game in the majors since 2011. Zimmer exists on the periphery of the discussion. As he rebuilds arm strength, his development “is going to be a slow thing” this year, Picollo said. He would not rule out starting Zimmer in extended spring action, but stressed the organization’s preference involved him opening the season in either Class AA or AAA.