"It was my own fault, just kind of letting off the gas pedal," Miller said. "Figuring I already had this game, I was going to go deep into the game. I already had it figured out and I stopped executing pitches."
Miller served up a three-run homer to Joey Votto in the sixth and ended up exiting the game before he could record an out in the frame. As a result, the Cardinals' bullpen had to cover the final four innings.
"I lost focus, I guess, something you shouldn't do as a starter," Miller said. "That could've gone completely different. The way it ended, it shouldn't have. You can look at my stats for [the game] -- it's nothing like how I performed."
For Miller, it proved to be a lesson learned. Such is life for a 22-year-old pitcher with only 22 big league starts under his belt.
"You're just constantly learning," said manager Mike Matheny. "We have to keep reminding ourselves how young a lot of these guys are and Shelby is absolutely one of those in that group."
Zack Meisel is a reporter for MLB.com. Follow him on Twitter @zackmeisel. This story was not subject to the approval of Major League Baseball or its clubs.