After the first practice of training camp Thursday, 49ers head coach Jim Harbaugh described the feeling of his team as "relentlessly positive."And, after an offseason with several significant moves, San Francisco certainly is surrounded by high hopes entering the 2014 season.After three straight trips to the NFC Championship Game and a Super Bowl appearance since taking over the team in 2011, Harbaugh's excitement Thursday was effusive.He said the first day of training camp is a big, exciting change from the offseason routine, when suddenly, he said, "It's light, it's bright, it's noisy, it's the crazy world of football."But while Harbaugh was his typical enthusiastic self and 49ers players expressed their happiness at getting back on the field and starting work toward 2014, others outside the organization have reservations.In writing a preseason analysis on the Niners for USA Today this week, Steven Ruiz wondered if the 49ers' magical run may soon lose steam."With the bulk of the team's core group headed toward free agency in the next two years, the window for the franchise's sixth (Super Bowl) championship is starting to close," he wrote.Certainly, the 49ers will have some...