Starbucks is in trouble again. In its last quarterly-earnings report, it announced disappointing results, including a 4% drop in same-store sales (11% in China, its second-biggest market). After that announcement, its stock plunged. (It is still well below its 12-month high.) And its founder and three-time CEO Howard Schultz once again fired off a missive on LinkedIn pleading with Starbucks’ current leaders to rediscover and embrace the company’s core purpose, its reason for existence.