SAN FRANCISCO — Even two decades ago, before the boom of analytics, Buster Posey would have been a bit of an outlier in an MLB front office. These days, when most are filled with recent Ivy League grads, a former MVP who now serves as a president of baseball operations is practically a unicorn.Posey’s background put him in a fascinating spot recently when it came time to make the biggest decision of the Giants spring. Like Bryce Eldridge, Posey was once a first-round pick and top prospect who quickly earned a September cup of coffee. Like Posey in 2010, Eldridge was disappointed when he found that he wouldn’t break camp with the team.The decision was not Posey’s alone, but the buck stops with him, and he decided that Eldridge should at least initially follow the same path he did. Asked a few days later about what he wanted for Eldridge, Posey said it was simple. “Just play baseball,” he said. Posey, Zack Minasian, Randy Winn and the rest in the front office are determined to give their best prospects a bit more time to develop after years of watching Giants minor leaguers get rushed and flame out. Eldridge has fewer than 1,000...