In what wound up as a disheartening 6-3 loss to the Rangers on Monday, Smoltz was tagged for three home runs in that sixth.
The Red Sox never recovered, and fell into a tie with the Yankees for first place in the American League East.
"You shake your head and you move on, and that's exactly how I approach it," said Smoltz. "The next start will be at home, and I want to come out and execute."
But that didn't make this one any easier for Smoltz to swallow.
For perspective, consider it was the first time Smoltz gave up three home runs in an entire outing since June 8, 1997. It also marked the first time he fell victim to as many as three long balls in an inning since June 19, 1994, when the Reds greeted him with four in the first inning.
Such ancient history being dredged up seemed far from likely the way Smoltz started, firing 75 pitches over the first five innings and taking a 2-1 lead into the sixth.
"You look in the scorebook, you look in the paper, you think I pitched a bad game again," said Smoltz. "I'm trying my best to not get frustrated over the results. They do frustrate me. I felt like the game was well in hand. One pitch, I'd like to have back. At the end of the day, I gave up six runs and I shake my head. I battled, [but] it's unacceptable."
The dramatic shift in momentum started when Michael Young led off the sixth with a 424-foot equalizer to left-center on a hanging slider. Josh Hamilton followed with a double, and with one out, Hank Blalock gave the Rangers their first lead on an RBI single to right.
However, the moment that Smoltz expected would keep him tossing and turning in his hotel room into the wee hours of Tuesday morning was still to come.
With two outs, David Murphy -- a former Red Sox prospect -- unloaded for a two-run homer to right. Smoltz slipped as he was about to deliver the pitch, and it wound up going into the wrong spot.
"I slipped. But still, for him to hit it ... I hit the side of the mound," Smoltz said. "I pulled the fastball in. It was supposed to go away, and he golfed it. Tip your hat to him, but it was certainly not the pitch I wanted to make. The two-out runs are getting a little bit on my nerves."
Jarrod Saltalamacchia made it back-to-back, ripping a solo shot that made it 6-2 Rangers and knocked Smoltz out of the game.
"Smoltz was throwing a great game," Young said. "For a lot of us, it was the first time seeing him. He still has good life on his fastball and good bite on his breaking ball. He was throwing a great game. We were fortunate we had some guys string together some good at-bats and get a big inning going."
The big inning has been the big problem for Smoltz this season. In five starts since being activated, Smoltz is 1-3 with a 6.31 ERA.
"I'm frustrated, but yet still pleased with the way I'm throwing the baseball," Smoltz said. "The results have been awful. They have not matched the effort or, for what I think, the results."
The Red Sox have hardly lost patience with Smoltz.
"He's still playing catch-up quite a bit, not only with his health, but with the game," said Sox catcher Jason Varitek. "I firmly believe that."
The Sox won their first game after the All-Star break, but they have lost the last three, marking their longest skid since another three-game slide from May 13-15.
Early on, the Red Sox looked to be the aggressors. Kevin Youkilis sparked a two-out rally in the top of the first, hitting a single that Murphy lost in the sun. David Ortiz followed with an RBI double off the wall in center, and Smoltz had a 1-0 lead.
The Red Sox got to Rangers starter Kevin Millwood again in the fourth, with Varitek delivering an RBI double to right.
From there though, the Boston bats, which have struggled of late, couldn't get anything going.
Blalock answered for the Rangers in the bottom of the fourth, cracking an RBI double to center that sliced the Sox's lead to 2-1.
As it turns out, it wasn't nearly enough for Smoltz.
"I'm going to have a hard time sleeping tonight, because I don't think today was a performance where I should have given up six runs," said Smoltz.
Ian Browne is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.