For all four, however, San Francisco is the destination they've been seeking all year.
"It's definitely nice to be back," said Espineli, who appeared in nine games with the Giants from July 20 to Aug. 13. "Getting sent back down, all you think about is trying to get back here every day."
Misch and Bowker also spent time in the Majors this season, giving manager Bruce Bochy a better indication of how far they've progressed.
"It certainly helps your evaluation process when you get more than just the month of September," he said. "But all the information you can get, whether it's one month in September [or more], certainly helps the evaluation process."
Bochy said both Misch and Espineli will be used out of the bullpen, while Bowker will either play first base or the outfield and mostly come off the bench. Schierholtz, however, was immediately inserted into the starting lineup to give Aaron Rowand a day off.
"It's good to have him up here and give him a chance to play and show what he can do," Bochy said. "He can hit, play outfield, run. We think a lot of Nate Schierholtz."
Schierholtz's journey back to the big leagues was a lot more indirect than his Fresno teammates. After spending the entire season with the Grizzlies, Schierholtz traveled to Beijing to play for Team USA in the Olympics.
"It was one of the best baseball experiences of my life," he said. "There were so many memories that I'll remember forever."
One of Schierholtz's best memories was defeating Japan to win the bronze medal. But that wasn't what his Giants teammates were most interested in. They wanted to here about Schierholtz's controversial collision at home plate with Chinese catcher Yang Yang.
"I didn't realize it was shown that much until I got home and saw it on the front pages of the newspaper," he said. "It was kind of surprising because I didn't really think it was that big of a deal. But they play baseball a little different than we do over here, so it was a big deal to them."
Right now, nothing is a bigger deal to Schierholtz and the other callups than proving they belong in the big leagues.
"This is where you want to be," Espineli said. "With everything that's going on and all these young guys up here, hopefully I can stand out and show that I deserve a good look come Spring Training."