Ryu is 3-2 with a 3.00 ERA in seven starts this season, with 31 strikeouts and 11 walks in 39 innings. He has been sidelined with left shoulder inflammation since his start against the Rockies on April 27 at Dodger Stadium. He threw a 40-pitch bullpen session on Tuesday in Los Angeles, then threw a simulated game on Friday in Arizona in preparation for his return to the Dodgers starting rotation.
Jacob deGrom is scheduled to start Wednesday for the Mets, making his second major league start.
The Dodgers will need to make a corresponding roster move to add Ryu, but it appears likely what the decision will be.
Paul Maholm allowed 10 runs in his last start, has a 5.40 ERA and a strikeout rate of 7.7 percent that ranks 366th among the 368 major league pitchers to have thrown at least 10 innings this season. But it appears he'll stick around for now.
It could be Mattingly posturing and simply not tipping his hand at the move until it needs to be made, but the fact remains if the team was done with Maholm it could have designated him for assignment already and had an extra relief pitcher for these games in the interim before Wednesday.
Barring injury, it's more likely that Chris Withrow's options will seal his fate with a trip to Triple-A Albuquerque. That, and his 12 walks in his last 10 appearances.
Slotting in Ryu on Wednesday helps take advantage of the off days surrounding the Arizona series. The three starters this weekend in Phoenix — Zack Greinke, Clayton Kershaw and Dan Haren — will make two straight starts on extra rest.