Dodgers’ Yoshinobu Yamamoto likely will be placed on injured list

A noticeable drop in the velocity of his four-seam fastball in the first inning was the first sign that something was not right with Dodgers right-hander Yoshinobu Yamamoto on Saturday night.

The red lights then began flashing after the top of the second, when SportsNet LA cameras caught pitching coach Mark Prior hurriedly summoning manager Dave Roberts and an athletic trainer into the tunnel below the dugout and reliever Michael Grove began warming up in the bullpen.

Sure enough, Yamamoto was pulled after giving up one hit in two scoreless innings of an eventual 7-2 loss to the Kansas City Royals in front of a crowd of 50,423 in Dodger Stadium, the team announcing an initial diagnosis of triceps tightness.

“It’s a high possibility,” Roberts said, when asked if Yamamoto would be placed on the 15-day injured list as a precaution. “But we’ll get our doctors involved, and see if there’s more to it.”

Yamamoto said through his interpreter that he began feeling tightness in his triceps this past week, after he threw a season-high 106 pitches while shutting out the New York Yankees on two hits through seven innings on June 7, and “that was the reason” his scheduled Thursday night start against Texas was pushed back to Saturday.

“I was feeling it a couple days ago,” said Yamamoto, who signed a 12-year, $325-million deal in December. “But today, that tightness was gone.”

But the tightness returned during pregame warmups, and Yamamoto said he “was communicating with my coaches about that.”

Why did Yamamoto make the start if he was feeling tightness before the game?

“I was very aware of it, but it was not that serious at that point,” he said. “Then, as I was pitching, it started [to get worse].”

If Yamamoto did tell Prior and assistant pitching coach Connor McGuiness that he felt some tightness warming up, “I obviously wasn’t part of that conversation,” Roberts said. “But there was no point in time where we felt he couldn’t make the start going into today or today. Because if that was the case, he wouldn’t have made the start.”

Roberts seemed to be under the impression that Yamamoto was experiencing normal between-starts soreness.

“He felt some soreness after his last start, and we pushed him back,” Roberts said. “During a season, pitchers are always going to be sore, but he said he felt good enough to go. We wouldn’t pitch him if we felt he was going to put himself in harm’s way.

“If we had any inkling that all he could muster was two innings, we wouldn’t have pitched him tonight. … He had soreness during the week, which is why we pushed him back, but I didn’t know until the second inning that he couldn’t go back out for the third.”

Is it possible something got lost in translation?

“I knew that he was sore going into the start, but I didn’t feel there was any soreness that would put him in harm’s way today, so I don’t see how that’s lost in translation,” Roberts said. “There was nothing that we heard, either from the coaching staff or myself, that felt he shouldn’t have made the start today. There was nothing.”

Yamamoto, who is 6-2 with a 2.92 ERA in 14 starts, walked one in a scoreless first inning and gave up an infield single in a scoreless second, but his 12 four-seam fastballs were clocked between 92.9 mph and 95.9 mph, with an average of 94.2 mph. His 28th and final pitch was a 93.3-mph fastball that struck out MJ Melendez.

Yamamoto threw 29 pitches that were clocked at 97 mph or higher in his June 7 start in Yankee Stadium, which he attributed to “my mechanics working very well.”

His four-seamer on Saturday night was down 1.3 mph from its season average of 95.5 mph. The velocity of Yamamoto’s secondary pitches were also down, his curveball by 2.4 mph and his split-fingered fastball by 2.9 mph.

“The last outing was not really directly related to this tightness,” Yamamoto said. “It’s more during the recovery process this week.”

If Yamamoto is placed on the 15-day injured list, he would be replaced in the rotation by right-hander Bobby Miller, who is scheduled to start Wednesday night’s game at Colorado after missing two months because of shoulder inflammation.

Saturday night’s game turned on an epic 12-pitch battle in the top of the sixth inning between Dodgers reliever Blake Treinen and Melendez, who fouled off six two-strike pitches and took a ball to work the count full.

Melendez then drove the 12th pitch over the wall in right field for a grand slam that turned a 2-1 deficit into a 5-2 Kansas City lead.

The Dodgers had taken a 2-1 lead in the fourth inning when Gavin Lux grounded a bases-loaded, two-out, two-run single to center field.

Dodgers right-hander Yohan Ramirez retired the side in order in the fifth, and Treinen, who returned from a shoulder injury to open his season with 14 scoreless appearances in which he struck out 19 and walked only two in 13 innings, took over in the sixth.

The veteran right-hander got Bobby Witt Jr. to fly out to the warning track in left for the first out but uncharacteristically walked the next three batters, prompting a mound visit from Roberts.

Treinen struck out pinch-hitter Adam Frazier with a wicked 83-mph slider, but he could not retire the stubborn Melendez, who boosted Treinen’s ERA from 0.00 to 2.63 with his game-turning slam.

The Royals added two insurance runs off left-hander Anthony Banda in the seventh for a 7-2 lead, Garrett Hampson sparking the rally with a leadoff triple and Witt (single) and Nelson Velasquez (sacrifice fly) driving in the runs.

Seth Lugo, the veteran right-hander who signed a three-year, $45-million deal with Kansas City last winter, gave up two runs and six hits in six innings, striking out four and walking one, to improve to 10-2 with a 2.40 ERA.

Max for the minimum

Max Muncy’s recovery from a right rib-cage strain will stretch into a second month. The third baseman, who went on the injured list on May 17, is fielding ground balls, throwing and running, but he won’t swing a bat for at least another week.

“Honestly, I don’t know what his timeline is,” Roberts said, “but it’s even slower than I think we all expected.”

Muncy was batting .223 with a .798 on-base-plus-slugging percentage, nine homers and 28 RBIs in 40 games when he got hurt. He thought he would return in two or three weeks but felt a “twinge” in his rib-cage while taking batting practice in Arizona in late-May and has been unable to resume swinging a bat.