"It was supposed to be away, and I missed middle in," Jackson said of the 94-mph fastball he threw to Kozma, the first pitch of the at-bat. "Something for if he is being aggressive and is trying to turn and burn, it was a perfect pitch for him."
The homer was only the third in Kozma's two-year career, and it marked the fifth hit Jackson surrendered in the six at-bats after he retired the game's first two batters. The right-hander eventually rebounded, allowing only a single and a double over the next three innings.
But with Washington's bats falling silent -- the club finished 0-for-8 with runners in scoring position and left 11 men on base -- there was no margin allowed for a weak start. Jackson finished the regular season with a 6.97 first-inning ERA -- the highest of any inning by more than 2.00 runs -- and a 4.75 second-inning ERA.
"He couldn't get the ball down early, that was the key," manager Davey Johnson said. "When he starts throwing a lot of quality strikes on the knees, early in the game, he usually throws a strong game. But he was up from the start, and you can't do that against a good-hitting ballclub."
Given his seven postseason appearances -- including four starts -- Jackson spent much of the early portion of the NLDS facing questions about the benefits of playoff familiarity. The 29-year-old is the oldest pitcher among the Nationals' starting rotation, and the only one with postseason experience prior to this season. But after Wednesday's outing, Jackson's postseason ERA now lies at 5.33.
Several factors could have been at play, and many were suggested to him postgame. Without using it as an excuse, Jackson referenced the Cardinals' free-swinging approach as something the Nats have seen from them all year long.
"They're not waiting around for you to pitch strike one," Jackson said. "They're coming out and jumping on pitches early in the count."
Another potential influence could have been the lengthy amount of rest Jackson received after pitching the regular-season finale on Oct. 3. With at least six days of rest this season, Jackson went 1-3 in six starts with a 5.34 ERA -- though he also declined the notion of too much rest being an issue.
"I didn't feel like I was out of rhythm, I didn't feel like I couldn't throw strikes," Jackson said. "I just missed across the plate, and they hit a couple balls that cost me."
One final element that was a persistent storyline entering Wednesday's start was Jackson's familiarity with the Cards, and vice versa. Jackson was traded to St. Louis in late July 2011, and in 13 games (12 starts), he went 5-2 with a 3.58 ERA. He also made four starts for the eventual World Series champions in the 2011 postseason, going 1-1 with a 5.60 ERA over 17 2/3 innings.
After signing a one-year deal with the Nationals in February, Jackson went 1-1 with a 7.71 ERA in two starts against the Cardinals this season.
"We faced Edwin the last week of the season and had a pretty good idea [of what we wanted to do]," Cards catcher Yadier Molina said. "We had a good plan against him, and we executed.
"We know everything about him. The main thing is to execute. That's what we did tonight."
Trailing the series two games to one, the Nats' postseason hopes rest on Detwiler's Game 4 start. Whether the 26-year-old left-hander comes through in his first postseason appearance will be the dominant pregame storyline, and Jackson said all Detwiler has to do "is just do what he's been doing."
But thanks to his one-year contract, Jackson is also facing something else -- the specter of having already pitched his last game as a National.
"It could be, it could not be," Jackson said. "That definitely is not a way you want to end it. Hopefully we come out and we're able to get a game [Thursday] and get the last game with Gio [Gonzalez] going, but we'll be taking it one game at a time. You definitely hope the season doesn't end like that."