Put aside the final result -- a 5-1 loss by the Red Sox -- for just a second.
Penny's stuff was probably the best it's been all season, and one meaty fastball to Ian Kinsler -- pummeled over the Green Monster for a three-run homer in the fifth inning -- proved to be a game-breaker.
"I sped the game up instead of slowing it down," said Penny. "I got ahead of myself, started thinking about not one pitch at a time but the second and third pitch I was going to throw. It happens. I made a bad pitch to Kinsler. I just got ahead of myself. I lost focus for a little bit -- made a couple of bad pitches."
The 2-0 pitch was supposed to tail away and it ran right over the heart of the plate.
On a night Rangers right-hander Kevin Millwood mowed the Red Sox down (seven-plus innings, seven hits, no earned runs, five strikeouts), it was a damaging turning point. The right-hander improved to 4-1 with a 2.90 ERA in eight career starts at Fenway.
Seldom are the Red Sox (32-23) quieted to that degree at Fenway. Boston stranded 13 runners.
"You can credit a lot of that to Millwood," said Red Sox catcher Jason Varitek. "He threw the ball well, made pitches when he needed to. He cut the ball, he sank the ball. He was able to change speeds, mix in curveballs, changeups and he threw the ball really well."
The Rangers, however, aren't used to that type of success at Fenway, as they were able to win at Boston for the first time since July 1, 2007, snapping an eight-game losing streak.
As accountable as Penny was for his mistake pitch, the whole night could have been different if Elvis Andrus -- who came up before Kinsler -- had been retired on a crisp ground ball toward the hole on the left side of the infield.
Off the bat, it looked like a play shortstop Julio Lugo might have been able to make. Instead of serving as the third out of the inning, the ball rolled under his glove for an RBI single, creating the chance for Kinsler. Since returning from right knee surgery on April 27, Lugo has struggled to regain his range.
"The guy's diving for the ball and trying to catch it," said Red Sox designated hitter David Ortiz. "What else can you do? It's not like he's not hustling. The guy had surgery on his knee. He's trying."
Penny also chose not to make Lugo a scapegoat.
"They were playing a little bit up the middle," Penny said. "Again, that wasn't a great pitch. You don't want to be in a 3-2 count where they start the runners. You can't get in that situation as a starting pitcher. It just kills you."
Already on a roll, Millwood (5-4) became that much tougher with a cushion to work with.
"I think once the guys put some runs up on the board, it gave me a chance to relax a little bit and throw the ball over the plate," said Millwood.
It became a 5-0 game in the fifth, with Chris Davis ripping an RBI ground-rule double to right.
Over 5 2/3 innings, Penny (5-2) gave up seven hits and five runs. He walked two and struck out five.
"His first four innings were as good as we've seen," said Red Sox manager Terry Francona. "He was throwing the ball really, really well. Then the next two, I think he threw 50 pitches."
After being stifled over the first seven innings, Ortiz gave the Red Sox some semblance of life with an RBI single in the eighth. The Sox had first and second and none out, and the Rangers (32-22) went to left-hander Eddie Guardado. The veteran got the job done, striking out Varitek, getting Jacoby Ellsbury on a routine flyout to left and retiring pinch-hitter Rocco Baldelli on a hard grounder to second.
Meanwhile, Penny was left to ponder why his quality stuff didn't turn into a quality start.
"It makes it a little tougher," Penny said. "I'll just work on the things I need to work on between starts and get back out there."
Ian Browne is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.