• September callups and roster rules explained
"A couple of relievers, maybe a hitter," Mackanin said. "They don't know who they are yet, so I can't tell you who they are."
The Morning Call in Allentown reported late Wednesday night that left-hander Patrick Schuster, right-hander Colton Murray and first baseman Darin Ruf will be promoted. Ruf has been hitting well -- .298 with 20 home runs, 65 RBIs and an .895 OPS -- with Triple-A Lehigh Valley.
"I would like to give [Ruf] another chance, but there are so many guys we have to look at," Mackanin said. "I don't know what we're going to do."
Prospects such as Jorge Alfaro and Roman Quinn also could join the team once Double-A Reading's season is finished. It seems unlikely that Triple-A prospects J.P. Crawford and Nick Williams join the Phillies before the end of the year.
Others could be promoted, too. But playing time already is tight, which is something Mackanin will have to work through.
"It can sometimes be too crowded, and you know," Mackanin said, "it is what it is. It happens every September. I can't give playing time to a lot of guys. Perhaps guys who have earned the opportunity to come up, maybe that's the main reason for it. For the prospects -- we're not going to bring up a prospect to sit. We want him to play."
Todd Zolecki has covered the Phillies since 2003, and for MLB.com since 2009. Read his Phillies blog The Zo Zone, follow him on Twitter and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.