Boston held a nine-game lead in the American League Wild Card standings, and clung to a half-game lead in the AL East. The Braves were up by 8 1/2 in the National League Wild Card chase.
How could anything possibly go wrong? No team in baseball history had ever held a lead as large as the Braves or Red Sox did entering September and not qualified for the postseason.
But in this case, a simultaneous epic collapse was in motion.
Even if it had been a steady, four-week tumble for both teams, the end was jarring in both cases.
The Red Sox were one strike away from victory, and forcing at least a one-game playoff, only to have Jonathan Papelbon blow just his third save of the season. They could have at least settled for a one-game playoff against Tampa Bay if the Rays hadn't pulled out a miraculous 8-7 victory over the Yankees on Evan Longoria's walk-off homer. The Red Sox, World Series favorites in the eyes of many when the season started, were headed home.
Braves closer Craig Kimbrel suffered the same misfortune as Papelbon, letting a one-run lead get away in the ninth. The Phillies wound up winning that game in the bottom of the 13th, and so the Cardinals were the NL's Wild Card team instead of the Braves.
Though the ending felt like a bad car crash in both cases, the teams should have seen it coming.
For a team as loaded as the Red Sox to go 7-20 in September, something -- other than simply an agonizing loss in the season's final game -- had to be very wrong.
"Yeah, when you have the kind of month that we have, as it develops, you worry that you're not going to accomplish your goals," said Theo Epstein after what proved to be his final game as the general manager of the Red Sox. "We sure didn't. It's impossible to explain -- a huge disappointment. We have no one to blame but ourselves. We did this to ourselves."
They did it to themselves for a variety of reasons, but the biggest one is that they stopped pitching.
Josh Beckett and Jon Lester stumbled in September when the team needed them to pitch like aces.
"It bothers me, because I'm supposed to be a stopper," Lester said. "I picked a terrible time to stink. That's on me."
With Clay Buchholz down with a back injury, none of the other starters stepped up. With Beckett and Lester slumping at the same time, everyone from Tim Wakefield to Erik Bedard to Andrew Miller also faltered. Boston's rotation posted a 7.08 ERA for the month.
For the Braves, the biggest problem was their offense, as they hit .235 with an anemic .357 slugging percentage in September. Brian McCann (.200 with two homers) and Martin Prado (.236 with a .257 on-base percentage) slumped just as much as Beckett and Lester did for the Red Sox.
Chipper Jones thought he had seen it all in baseball. But he had never seen anything like this.
"I thought we had a great year up until September," said Jones. "We played 4 1/2 good months of baseball. That's not to be overlooked. We were in prime position to achieve our goals, and we came up two games short. When you come up two games short, it's easy to look back and think about how many games we gave away. You think, 'Golly, what if I could have seen that ball in the lights in Florida? Or if we didn't walk a guy here? Or if we had gotten the hit there?'
"There are a lot of what-ifs. But if you sit around thinking about what-ifs, you're going to drive yourself insane. Sometimes the ball just doesn't bounce your way. That's probably simplifying it too much. But it keeps you sane."
Perhaps in a market such as Atlanta, without the intense media, sanity is easier to keep.
But in Boston the collapse started a chaotic period. Terry Francona parted ways with the club after a memorable eight-year tenure as manager. Epstein, having already snapped one epic championship drought in Boston, took a job in Chicago, where he will try to do it again with the Cubs.
In addition to from the turnover at the top, there were subplots. Stories, which were later confirmed, came out that Red Sox starting pitchers were drinking beer and eating fried chicken during games in which they weren't playing. There were changes in the medical and training staffs after it became clear that not every player was in the best physical condition possible.
"Are there things I regret? Sure there are," Lester said. "But nothing happened that had me unprepared to pitch. I don't blame people for wanting answers, because we had a [great] a team, and we lost. You can't have a team that gets paid like we get paid and loses and not expect people to want answers."
Neither team was particularly lucky in September, either.
David Ortiz hit a bullet off the right-field wall one September night at Fenway that would have tied the score. It was called foul, even though replays showed it was fair. The Red Sox lost by a run. Jones lost a ball in the lights for the Braves, and naturally, they lost.
"When you lose a ground ball in the lights and the next guy hits a two-run homer to beat you, you kind of get the feeling something is out of your control, something is going on," Jones said. "It seemed like from that point on, we were playing more to protect the lead than to try to extend it."
Without question, both the Red Sox and Braves lost their edge in September and never got it back.
The consequence, aside from not making those planned trips to the postseason? Infamy of historic proportions.