Myers allowed four runs on eight hits and a walk with five strikeouts for the Phils, who had won six of their previous seven.
"I haven't seen the fastball," Phils manager Charlie Manuel said. "It topped out today at 89 [mph]. Myers is usually at, what, 92, 95? Somewhere in there. I haven't seen the fastball since the start of the season."
"They say you go through dead-arm periods, but usually it's never lasted for six starts," Myers said in the clubhouse after a lengthy postgame meeting with Manuel. "I'm not the guy that's going to make excuses or anything like that. [But] it's tough for me to try to pitch with that when I never really have before. It's kind of a learning experience also. Not every game are you going to feel good, but at least I'll have something on the ball. But right now, I am throwing 86 mph fastballs and trying to let it go."
Eric Bruntlett's RBI single in the fifth scored Pat Burrell, who had doubled, to account for Philadelphia's only run. Those were the only two hits the Phils collected against Maholm (2-2), who walked four and faced only three over the minimum. It was his third complete game and first since Aug. 13, 2007, against the Giants.
"He threw strikes and he had a low pitch count, and we swung the bat," Manuel said. "I felt like we hit a few balls real good and they caught them all. But at the same time, I have to give him a lot of credit because he pitched a good game."
Maholm was aided by some sterling defense -- including Xavier Nady robbing So Taguchi of a double with a diving catch down the right-field line -- that included two double plays and a caught stealing. But Maholm had four 1-2-3 innings and retired the final eight hitters and 11 of the final 12.
"He threw good today," Phils third baseman Pedro Feliz said. "He was changing speeds, trying a cutter and fastball away. It's just one of those days when the pitcher had it. He's a great pitcher, but I don't think he can do that every day. Today, he did a good job."
It was apparent from the first batter of the game that Myers wasn't on his game. For the second time in his career, McLouth led off with a homer, driving the ball deep into the right-field seats. The Pirates made it 2-0 in the fourth against Myers (2-2) on a Bautista RBI single, scoring Adam LaRoche. The Phillies avoided further damage when Bautista was thrown out at the plate by Jayson Werth on a Luis Rivas single to center.
McLouth hit his second homer of the day to right, his sixth, on a 2-1 pitch in the fifth after a leadoff walk to Maholm that gave the Pirates a 4-1 cushion. It was the 500th Pirates home run in the eight-year history of PNC Park.
"Normally in that 2-1 situation, if I am throwing 92 or 93, I am going at him with a heater," Myers said. "Maybe I am kind of pitching backwards without it."
Pittsburgh made it 5-1 against reliever Rudy Seanez in the sixth when LaRoche scored on a double-play ball hit by Rivas.
The Phils had won each of Myers' past three starts, but he has lasted more then five innings in only three of his six outings. Though it's not time to panic yet, Myers sounded as if he was starting to get worried.
"[My] mechanics feel fine, everything feels normal," Myers said. "I'm not seeing anything different. It's just that the fastball's not coming out good right now. Everything's the same speed. If you throw an 86 mph fastball and 82, 83 mph cutter, there's no difference in speed there.
"The thing I can't figure out is it's not like [my arm is] hurt, and it's not like it's aching. It's not like I can't throw or anything like that. I've had it times where it is barking a little bit and still go out there and throw 92, 93, something like that. But right now, it just isn't coming out."
Myers, who said his workout regimen wasn't any different than any other offseason, said he won't change anything between starts.
"He's supposed to be one of our aces," Manuel said. "And I haven't seen his good stuff. Today he couldn't get the bottom of the order out and that hurt him. Every time he goes out there, I'm looking to see his good stuff. Today was not his good stuff."