Twins righthander Trevor May didn't pitch as badly as his line suggested Monday. But the bullpen sure earned every digit of theirs.

No area of Twins baseball can be absolved right now, and their home opener against the Royals was an exercise in all-around awfulness. But Monday's game offered more early evidence that the pitching staff has issues.

The staff ERA at start of the day was 5.88 — last in the majors — and soared to 6.52 when Twins pitchers gave up 10 earned runs to the only undefeated team in baseball. The afternoon was punctuated by the Royals' six-run eighth inning, during which the Twins used four different relievers. The bullpen was a playpen on Monday.

This might play into manager Paul Molitor's thinking down the road: May, called up to replace the injured Ricky Nolasco in the rotation, wasn't that bad Monday. He threw first-pitch strikes to 10 of the first 16 batters he faced. He was unpredictable with his pitches and was mostly around the plate. And he busted some hitters inside. Through five innings, May had thrown only 55 pitches and the Twins trailed only 2-1.

Then May gave up a single to Mike Moustakas to start the sixth. Then a fastball down the runway was powered into the right-center field gap by Lorenzo Cain — who has become an offensive threat — to score Moustakas. May can't be blamed for Torii Hunter throwing to no one in the field, allowing Moustakas to score and Cain to advance to third.

Eric Hosmer doubled to left-center on a ball a good outfielder catches — but Oswaldo Arcia just missed.

Kendrys Morales, who homered off May in the second, lined out. The sound of May's pitches off the Royals' bats told Molitor it was time for the young righthander to have a seat.

"The third time around, [the Royals] started to have better approaches and the contact was a little bit more consistent," Molitor said.

May felt he had "a bunch more left in the tank," but the ball was turned over to the bullpen.

"I just looked at matchups and tried to keep the game within striking distance," said Molitor, who pulled May after 78 pitches.

Tim Stauffer, whose fastball was in the mid-80s during spring training, is now up to 88. He finished the sixth and pitched a 1-2-3 seventh but gave up a single and a walk to start the eighth. Molitor went back into the bullpen, with horrific results.

Brian Duensing hit one batter all of last season and two in 2013. But his second pitch, a two-seam fastball, hit Alex Gordon in the right leg to load the bases. So be it for lefty-on-lefty matchups.

J.R. Graham, the Rule 5 draft pick who throws 96 miles per hour, entered the game and hit Alex Rios with his first pitch, forcing in a run.

"I wasn't trying to hit him on purpose, but it is part of the game," Graham said. "You have to bounce back and get after more people. I need to bail them out after something like that."

That didn't happen. Graham did get Salvador Perez to hit a grounder, but shortstop Danny Santana bobbled it for an error as another run scored. Then there was a two-run single by Alcides Escobar, a passed ball, a walk to load the base and a walk to force in a fifth run. The Royals added a sacrifice fly to complete a six-run inning that had the sellout crowd fleeing for the exits.

The Twins searched around the league for bullpen help toward the end of spring training. They knew what was coming. They might have to shuttle arms between here and Class AAA Rochester, but they know what they have down there.

First-year pitching coach Neil Allen will be challenged to get the most out of a bullpen that has a Rule 5 draftee, two relievers learning a new league and few power pitchers.

As for Molitor, he might be tempted in the future to leave May in the game next time and give him a chance to clean up his own mess. Because letting that bullpen door open has not been the answer.

"As a bullpen we don't ever want an inning like that," Duensing said. "It was a big part of the ballgame. We were still in it. We had a good chance to shut them down and maybe get some momentum, but we let the floodgates open."

La Velle. E. Neal III lneal@startribune.com