Dodgers reliever Chin-hui Tsao unavailable through all 17 innings against Padres

The case shifted from curious to critical as Sunday’s game stretched into double-digit innings. Why was Dodgers reliever Chin-hui Tsao sitting in the dugout for the entirety of the game?

Tsao had pitched the night before. He had not pitched well, walking his last three batters and granting the Padres a victory on a walk-off walk, but the Dodgers were desperate enough to use Ross Stripling, their starter on Tuesday, for the final three innings. Why was Tsao not available?

After the 9-5 victory in 17 innings, Manager Dave Roberts offered a vague answer. He indicated Tsao had reported “some soreness,” though it was unclear what part of his body felt sore. That led to another question: Why was an injured, mostly ineffective pitcher not either sent back to the minors or placed on the disabled list?

“He was evaluated this morning,” Roberts said. “Came in and didn’t feel right. With the day game, it’s hard to get somebody in from Oklahoma City in time.”

And so the Dodgers played the longest game of the season with only 24 players. On the plus side, at least, Roberts said Tsao might have been available to pinch-hit or run.

Montas starts journey to majors

Frankie Montas, a talented pitching prospect acquired over the winter, made his 2016 debut while pitching in a rehab outing for double-A Tulsa. Montas struck out two and gave up a run on two hits. He is available to join the team in the first week of June.

Montas underwent a rib resection during the winter. He is finishing up a stay on the 60-day disabled list. He is expected to aid the Dodgers as a reliever.

Grandal passes X-ray test

Yasmani Grandal did not venture behind the plate Sunday, but he was able to take an at-bat. The night before, he left the game early after fouling a ball off his right ankle. An X-ray on the ankle came back negative, but the Dodgers gave Grandal a day off his feet to rest.

andy.mccullough@latimes.com

Twitter: @McCulloughTimes