The veteran reliever hit another checkpoint in his rehab over the weekend by pitching on back-to-back days for the first time with Triple-A Memphis. He breezed through both appearances and has now made eight scoreless outings since beginning a Minor League rehab assignment on June 30.
Since moving up to Memphis, Duke has allowed one hit and one walk in five innings. He's struck out five and not needed more than 15 pitches to get through an inning.
"As soon as I started my throwing program I felt like I was putting the ball where I wanted to pretty well," Duke told MLB.com after his appearance on Sunday. "The feel for my off-speed pitches came along really fast, so I feel like it's something where it's probably sped the process up, being as consistent as I have been, so I'm just going to try and stay where I'm at."
Duke's rehab assignment can extend through July 29, which means that if there are no setbacks, he'd be in position to rejoin the Major League roster almost exactly a year after being acquired at the non-waiver Trade Deadline.
Before that point, though, Duke hopes to pass a few more tests, including entering a game unscripted in the middle of an inning. He also noted that the club may try to have him pitch multiple days in a row again. All of this would be asked of Duke if he were in a big league bullpen.
"Just hats off to Zach and how he's worked and also to our medical team and how they've continued to be open-minded and use all the information that they have to push guys forward," manager Mike Matheny said. "There are a lot of positives that we're hearing. I would love to be able to throw him into the mix."
With Duke on the cusp of returning, the Cardinals may not find it so imperative to focus their Trade Deadline attention on bullpen help.
"It's been almost scary good how well it's gone," Duke said. "No setbacks at all, so I'm just kind of really thankful right now. Hopefully these last few days, next week or so, can continue that."
• According to assistant general manager Michael Girsch, the Cardinals were scheduled to put outfielder Randal Grichuk (lower back strain) through a more intense workout on Monday to see how he responded. If all goes well, the organization would like to have Grichuk making his first Minor League rehab appearance on Wednesday.
• Right-hander Zac Gallen was named the Texas League Pitcher of the Week and first baseman Luis Bandes the Appalachian League Player of the Week for their performances from July 10-16. Gallen, the Cardinals' No. 22 prospect according to MLBPipeline.com, allowed one hit over seven shutout innings last week in a victory for Double-A Springfield. Bandes finished the week 12-for-25 with a trio of three-hit games and 11 RBIs.
• The Cardinals were represented by catcher Ivan Herrera and infielder Pablo Gomez in Sunday's Dominican League All-Star Game. Both 17-year-old players were signed by the organization in 2016.