Chen faced the minimum in the first two innings and tossed a scoreless third before running into trouble in the fourth. Back-to-back singles by the Pirates' Freddy Sanchez and Adam LaRoche preceded Delwyn Young's three-run blast to center.
"It was a changeup," Chen said. "I didn't think it was that bad of a pitch. I want to look at the replay definitely. I thought it was a pretty good changeup, he stayed back and hit it over the fence. It was tough because I thought I made a good pitch."
For the second consecutive game, Kansas City grabbed an early two-run lead. But history repeated itself, as the offense sputtered after that against starter Paul Maholm.
"I don't know how to put it in words," said Billy Butler, who drove in the Royals' runs with singles in the first and third. "Just get ready for tomorrow. We lost, guys in here take it hard, and that's the way it should be."
Chen tried to get a run back in the fifth when he lined one to left field. The ball bounced into a nook where a fan reached over and grabbed the ball, initially putting Chen at second with a ground-rule double. But the pitcher was sent to first after the umpires had a conference.
Regardless, it was Chen's first hit since May 21, 2006.
"I don't have that much pop, and that's the only way I can get a double," Chen said. "I wanted to be in scoring position and hopefully cut the lead back. It didn't happen, but we'll keep working on that."
Chen lasted 6 1/3 innings, surrendering four runs and seven hits on 76 pitches. The lefty did showcase his pickoff move, twice getting the Pirates' Nyjer Morgan.
"I knew [Andrew] McCutchen and Morgan are good runners," Chen said. "They want to steal bases, so I say, 'You now what? I'm just going to make sure I keep an eye on this guy.'"
Besides Chen's hit, another unusual play occurred in the bottom of the seventh. Pittsburgh's Andy LaRoche lined one off the top of the wall and as the ball came down, it hit right fielder Jose Guillen in the nose. Guillen had to check it, and his bearings, before deciding to stay in the game.
After the game, Guillen said he was fine and manager Trey Hillman confirmed that there weren't any lasting effects.
Things looked positive early for the Royals offensively, as Willie Bloomquist tripled in the first. The three-bagger gave the Royals 28 on the season, tops in baseball. It was Bloomquist's first triple since June 6. Butler singled the center fielder home the next at-bat.
Bloomquist was the catalyst again when he singled with two out in the third. After stealing second, Butler drove in Bloomquist with another single. The RBI moved Butler past Guillen for the team lead with 34. It was also the 46th run Kansas City has scored in the third this season, which is the most the club has put up in any inning.
It was the seventh multi-RBI game for Butler this season and his first since June 13.
"That's big for us, but obviously we couldn't get anything going," Butler said. "That really doesn't matter either, it's just -- we just couldn't get it done."
Besides Butler and Bloomquist, the Royals' bats were mostly silent. The tandem collected four of the team's seven hits as the others went 3-for-24, with one hit being Chen's. Kansas City also hit into three double plays, two by David DeJesus.
Maholm lasted seven innings, giving up just those two runs on five hits.
"We've got to do a better job battling, trying to get the pitch count up there," Hillman said. "You're better off getting a guy like that out of the ballgame, but we weren't able to do it early enough."
The frustration seemed to escalate in the top of the ninth. With two outs, Miguel Olivo was called out on a check swing. Olivo was walking away from home-plate umpire Phil Cuzzi when the catcher said something that caused Cuzzi to toss Olivo.
Hillman said after the game it wasn't a close call -- that Olivo didn't go around.
"Yeah, it was frustration," Hillman said. "No doubt about it."