Diamondbacks pitching plans up in air for series vs. Nats

Right-hander Taijuan Walker’s placement on the paternity list threw a wrench in the Diamondbacks’ starting pitching plans for Thursday, and it figures to have a domino effect on the next couple of days.

Walker was replaced on Thursday with Patrick Corbin, who was scheduled to start Friday against the Washington Nationals, and taking Walker’s place on the roster was right-hander Matt Koch, who was recalled from Triple-A Reno.

As for what the club will do this weekend, that remains to be seen. Because Koch wasn’t needed in relief on Thursday, he could be an option to start Saturday, manager Torey Lovullo said. Right-hander Zack Godley had been scheduled to start Saturday, but he is slated to start Friday on normal rest.

Could the club then ask Walker to return to the rotation for Saturday night?

“We’re not counting on it,” Lovullo said.

Koch had an impressive debut with the Diamondbacks late last season, tossing 18 innings over seven games (two starts) and posting a 2.00 ERA. He exhibited good mound presence and threw 67.1 percent strikes, above the major-league average of 63.8 percent.

But Koch missed most of spring training with a hamstring issue, then ran into shoulder problems with Triple-A Reno. His results there, however, have not been good this season. In four starts, he has an 8.47 ERA, and he’s allowed 15 earned runs in 16 innings in three starts since returning from the shoulder problems.

“He has been throwing the ball OK,” Lovullo said. “His stuff, from what I’ve been reading and understanding, has been taking shape and been consistent.”

The Diamondbacks remain without right-hander Randall Delgado, who is on the disabled list with a flexor strain in his right elbow. He likely would have been a candidate to start were he healthy.