Derek Norris doubled and also drove in the A's only run on a sacrifice fly as Oakland lost its second straight after winning nine in a row.
The Tigers sent Parker (0-2) to an early shower with a barrage of hitting. He allowed a career-high eight runs on nine hits over 3 1/3 innings. Parker walked two and struck out two.
"I made a couple of good pitches and they hit them, and I made a couple of bad pitches and they hit them," Parker said. "I threw strikes. They were just up in the zone."
Neither Melvin nor Parker projected much concern over his start, and Melvin said he'll make his next start. If it were up to Parker, he'd probably want to be on the mound Monday just to wash out the memory of this start.
"I'm upset. I'm not happy with what's going on," Parker said. "I can't dwell on it either. I just need to get back out and play the game."
Norris said there's not one answer to Parker's situation. In fact, he thinks Parker is throwing just fine.
"He's really making good pitches," Norris said. "Guys are just getting hits. It's frustrating when they're finding holes and then you give up a big one and it gets you in a hole."
Norris feels Parker won't need to do much tinkering when he takes his next bullpen session. He suggested it's just a matter of luck.
"The guy has talent," Norris said. "He's got great stuff. He's a little unlucky right now. I know you can look at the stats and kind of say 'Yeah, sure,' but he's really not catching any breaks."
There's also something to be said for the Tigers lineup.
"There's just no breaks in that lineup," Melvin said. "They are solid one through nine. You look at [Jhonny] Peralta and he's hitting down in the order. He's a good hitter."
Tigers manager Jim Leyland has seen Parker in better days and knows his team may have been fortunate.
"We have the utmost respect for him because we've seen him really good," Leyland said. "It's like anything else. You don't have it every time you go out. Today we might have just caught him at the right time. But he'll get it together. He's good. He's got it all -- fastball, curveball and changeup."
The A's fell behind after two batters. Austin Jackson singled and Torii Hunter doubled him home. Victor Martinez drove in Hunter and the day never got better for Parker, who now owns a 10.80 ERA on the season.
"Jackson is hot right now, so is Hunter," Parker said. "Those guys can really set the table for their big hitters."
Jed Lowrie singled to open the fourth and eventually scored on Norris' sacrifice fly.
"We came back here swinging the bats as well as we can," Melvin said. "I still think we have a good offense. We just got shut down the last two days."
Anibel Sanchez struggled with his control but was never in trouble. He walked four but struck out eight. He gave up three hits in seven innings.
"He's just a good pitcher," Norris said. "He has a plan and he sticks to it. He does a good job of keeping hitters off balance and keeping his pitch count down."