Orioles catcher Welington Castillo, who has been on the disabled list for a week with right shoulder tendinitis that has bugged him since February, threw for the first time since he was shut down and felt no problems.
While Castillo is eligible to return from the DL on Friday, the plan is to have him not throw Wednesday, throw Thursday, then get another day off before throwing to bases Saturday.
After that, he'll be a candidate for activation.
"A lot depends on what [head athletic trainer Richie Bancells] and them say," Showalter said. "We've got a really good feel for what's going on there, and I would be real surprised today if he didn't feel good. We've been very cautious with that, but he is going to want to push. This guy, he's chomping to get back. We'll take it one step at a time whether he has to, needs to [have a rehabilitation assignment]."
Showalter said Castillo, who is batting .314 in his first season with the Orioles, has told him several times he doesn't believe he'll need a rehab assignment.
Santander shelved again: Rule 5 outfielder Anthony Santander, who was hampered by shoulder and elbow problems during spring training and was only just recently serving as designated hitter in extended spring training games, has been shut down again.
Showalter said Santander had an MRI-arthrogram that revealed a "mild UCL strain" in his elbow and will likely require a platelet-rich plasma injection.
"That means no throws for six weeks," Showalter said.
The Orioles are interested in keeping Santander, who needs to spend at least 90 days on the active roster this season to prevent him from being subject to Rule 5 roster restrictions again next year. If he doesn't hit that mark, the restrictions carry over for 2018.
Santander remains on the 10-day DL but becomes a candidate to go on the 60-day list if the Orioles need a 40-man roster spot.
Around the horn: Right-hander Gabriel Ynoa (hamstring) was feeling good Tuesday, Showalter said. The team placed him on the DL on Sunday, and the 10-day DL rules prevent a pitcher from going to a rehab game inside seven days from being deactivated, but Showalter doesn't anticipate it will take much longer for Ynoa to be ready. … According to the Elias Sports Bureau, the Orioles' streak of leading for 42 straight innings entering Tuesday's game. Most recently, the last club to do that was the Los Angeles Angels, who led for 43 straight innings from June 2-7, 2008.