Dodgers pitcher Hyun-jin Ryu has suffered a setback in his recovery from a left shoulder impingement that has sidelined him since spring training, and has been slowed down in his rehab.

Ryu threw a pair of bullpen sessions last week at Dodger Stadium, then was going to travel with the team and throw to hitters on Monday in Milwaukee, but that plan was scrapped. On Monday, manager Don Mattingly said the plan shifted, for Ryu to throw to hitters in Los Angeles instead, but even that hasn't happened yet.

From Ken Gurnick of MLB.com:

"They've slowed him down a little bit," the Dodgers manager said of his No. 3 starter, who was suddenly scratched from making this trip after lack of velocity during a Friday bullpen session sent up a cautionary flag. Ryu was shut down near the end of Spring Training in hopes of calming the inflammation that sidelined him twice last year, but there now are signs that the injury is more severe. "You're always concerned with a starter," Mattingly said. "From the standpoint that they've slowed him down at all, you think about it a little bit. But I haven't had a major sign that I should be really concerned."

Some more specifics from Zach Helfand of the Los Angeles Times:

The Dodgers are still being cautious with Ryu, who threw a bullpen session on Friday. His velocity was at about 82 to 83 mph, Mattingly said, which was below what the team was comfortable with. Ryu hasn’t thrown since, to allow him extra days to rest.

Finally, from Bill Plunkett of the Orange County Register:

"They decided to give him some days off," Mattingly said. "They thing it's just that tired arm thing you get in spring training."

Even before this setback, the timing of Ryu's comeback has been largely unknown, with nobody in the organization willing to comment on record as to any sort of return timetable, other than Ryu laughing and saying "of course" he would be ready by the All-Star break.

Ryu last threw in a game on March 17, so given that we are already seven weeks removed from his last competitive time on a mound he was already facing a reasonably long rehab process once he finally got started, which looked like it might happen as soon as this weekend.

That won't happen now.

Whenever Ryu is able to begin any type of rehab assignment, he would likely need almost a spring training's worth of starts — say, between four and six, each one progressively longer — to build up arm strength, so you can as a rough estimate add a month to whatever start date he might have for a tentative major league return.

So we are already into June, and probably mid-June at the absolute earliest for Ryu, and likely the same if not later for Brandon Beachy, who is recovering from his second career Tommy John surgery and is currently partaking in the undefined itinerary of throwing bullpen sessions — Tuesday's session did not go so well, writes J.P. Hoornstra of the LA Daily News.

Last week Andrew Friedman said he didn't expect to be able to make any sort of significant trade for pitching until June at the earliest.

"Historically April and May trades are pretty uncommon," Friedman said last week. "For the most part we're going to work from inside. We have a number of really interesting candidates."

In other words, the Dodgers will have to get by with what they have for now, and likely for the next four to six weeks as well. Joe Wieland didn't do so well in his first crack at the rotation on Wednesday. Carlos Frias did well in his first try and gets another shot on Thursday. The Dodgers will have to find a way to mix and match and find a combination that works out of Wieland, Frias, Mike Bolsinger and Zach Lee, and hope that holds up.

Right now, that's their best option, and really their only option. Which, frankly, is a little frightening.