Red Sox slugger David Ortiz drives in Kevin Youkilis with Boston’s first and only run in the first inning of yesterday’s opening-day loss to the Kansas City Royals.

AP / Ed Zurga

KANSAS CITY — On the mound, he appeared lost. After the game, in the clubhouse, it was no better.

Curt Schilling had pitched poorly. Worse, he had no easy explanation.

What he had, more than anything, was that sick feeling.

Primed for his Opening Day assignment, Schilling struggled from the first inning. His day was over after the fourth, truncated by his inability to spot his fastball or command his secondary pitches.

Nasty, brutish and short — not what the Red Sox expected from their No. 1 starter. And certainly not what Schilling had expected from himself.

Some pitchers view an Opening Day start as an honor; Schilling sees it more as a responsibility.

“I made mistake after mistake,” said Schilling after allowing five runs in four innings in a 7-1 loss to the Kansas City Royals. He had required 89 pitches to produce just 12 outs.

There were 33 pitches in the first inning alone, and another 27 in the second. All of this from the same pitcher who took pride in his efficiency during spring training.

It had been nearly a decade since he had been knocked out of a start this early. (In 2001 with Arizona, he had a two-inning start but that was the result of a lighting failure that forced the cancellation of a game in San Diego).

There are times, of course, when every pitcher struggles and can’t find his stuff. But the good ones, the ones who have been around for 20 years like Schilling, find a way to battle through those starts.

Failing to do so isn’t just disappointing, the word Schilling used over and over again to describe his emotions — it’s irresponsible. His teammates were counting on Schilling yesterday, and from his perspective he failed them.

“Part of being a number one,” said Schilling, “is going out and winning when you don’t have your best stuff.”

And that’s what bothered Schilling the most yesterday: the fact that he couldn’t overcome his own shortcomings. Even with the maturation of Josh Beckett and the arrival of Daisuke Matsuzaka, Schilling correctly sees himself as the Red Sox’ ace — hence the Opening Day assignment.

This wasn’t a loss, then, in his mind. This was an abdication. Schilling, like every major-leaguer, can accept that failure is part of the game.

No, what bothered him yesterday was being a bad teammate. It didn’t matter that he didn’t have his best stuff. What mattered was that he didn’t make do with what he had.

Every run the Royals scored against him came with two outs. He was an out away from extricating himself from a bases-loaded jam in the first when he walked Ryan Shealy to force in a run. Schilling, who had walked just one batter in 21 innings in spring training, hadn’t issued a bases-loaded walk in the regular season since Aug. 7, 2005.

It was more of the same in the second. After a one-out triple by Tony Pena Jr., Schilling got David DeJesus looking at a called third strike. But before he could finish the inning, he allowed a run-scoring single to right by Mark Grudzielanek.

After a one-two-three third, the fourth inning was another workout. A one-out double followed by a walk didn’t seem harmful when DeJesus flied to left for the second out. But Grudzielanek drove an opposite-field double to right, scoring both baserunners, and Mark Teahan followed with an RBI single. More trouble after two were out.

“It was one of those games where I didn’t execute,” said Schilling. “I never made adjustments.”

He wouldn’t blame the poor showing on his changeup, which was his pet developmental project this spring. He threw just one in the first, and because of game situations, didn’t throw another until the third.

Unable to locate his fastball — which he customarily does with precision — or get quick outs with his splitter (just three groundouts), Schilling wasn’t about to fool around with a work-in-progress pitch.

Schilling struggling to throw his fastball for strikes? That’s about as rare as a “no comment” from the loquacious right-hander.

“He didn’t command,” said Terry Francona. “He was up with a lot of his pitches. It was tough for him right from the get-go — a lot of deep counts.”

Schilling pitches the road-trip finale Sunday night in Texas. It’s a safe bet that after yesterday, he won’t lack for motivation.

smcadam@projo.com