Rosenthal throws off mound, targets Sept. 14 return

PITTSBURGH -- It happened without an audience and well in advance of first pitch, but for the first time since July 25, Trevor Rosenthal threw off the mound on Monday.
It was a bullpen session of all fastballs, but for Rosenthal, it represented another step closer to a September return. The ousted Cardinals closer has reached the point in his rehab process where he has three bullpen sessions planned within the next week. That will be followed by live batting practice so that Rosenthal can test himself against hitters.
Those steps all lead toward Sept. 14, the date Rosenthal has circled for a potential return.
"I definitely feel like I'll be able to help out before the season is over," Rosenthal said. "[The discomfort] I was experiencing for most of the season, it's gone now."
Ironically, Rosenthal threw this first bullpen session back in the spot where he first felt something wrong with his arm. That was the first week of the season, when Rosenthal felt an odd sensation while warming up in the team's opening series at PNC Park. He continued to pitch through the discomfort, lost his job as closer and ended up on the DL with a 5.13 ERA.
"It's something that was definitely there [and] was causing me to mainly have issues with command and feel," Rosenthal said. "At least in my eyes, guys go through a lot of different things, and you just try to keep pushing. It wasn't working. Hopefully now I'll continue to progress and feel like I have in the past without an injury."
Here are other medical updates on several rehabbing Cardinals:
• Aledmys Díaz: After going 1-for-6 with two walks while serving as a designated hitter for Class A Advanced Palm Beach this weekend, Diaz has had his rehab assignment transferred to Double-A Springfield. After a day of rest on Monday, Diaz will work out with the Minor League team on Tuesday and start at short in Springfield's postseason opener on Wednesday. General manager John Mozeliak said that Diaz, who fractured his right thumb on July 31, could be back as early as this weekend.
• Jordan Walden: The reliever's season is all but over after he was unable to make an appearance in a scheduled rehab assignment due to continued discomfort around his right shoulder. Walden has been shut down and will return to Dallas to determine whether he'll undergo surgery. Walden, who hasn't pitched since April 2015, will be a free agent at the end of the season.
• Matt Holliday: He will have another scan of his surgically repaired right thumb on Wednesday, after which the Cardinals will learn whether the left fielder can resume baseball activities. Holliday has been working out at the team's Jupiter, Fla., complex since a pitch fractured his thumb. The Cardinals are still optimistic that Holliday will return this year.
• Michael Wacha: Wacha, who was shut down last month with a right shoulder stress reaction, has not had any setbacks since beginning a throwing program shortly after the Cardinals left on this road trip. If all continues to go as planned, Wacha should be throwing off a mound by the end of the week. Mozeliak said that the Cardinals are "very hopeful he pitches this year," though any return by Wacha would almost certainly be in a bullpen role.