Facing the hard-throwing Mets pitching staff, Seager was 3-for-16 (.188) with eight strikeouts. And with the season on the line in Game 5 of the NLDS, he forgot to cover third base out of a defensive shift.
The experience didn't exactly devastate the 22-year-old, who returned with a record-breaking season that sets him up with a good chance to be the NL Rookie of the Year and with a legitimate claim for down-ballot MVP votes.
The Dodgers need Seager to check off that postseason success box if they are to reach the promised land, and he said he's confident this fall will be much better than the last one.
"It's one of those things where you have to go through it to understand it and now I know what to expect," said Seager. "The veterans try to help, and looking back their advice was good to hear at the time, but it really isn't much help.
"I mean, I was still getting used to being in the big leagues, then you're thrown in there and it's not overwhelming, but in the playoffs you're even more uncertain what to do, what to expect. Honestly, right now I'm just more comfortable, and that will be the biggest difference.
Another difference, said Seager, is that because he was called up in September of 2015, he had never faced the Mets until the NLDS. By contrast, he's already played three games against the Nationals this year at Dodger Stadium and was 6-for-12 at the plate with a home run and two doubles. He was sick and missed the three-game series in Washington in July.
"The first time facing that team is never easy," he said. "This year having played the Nationals, you have somewhat of a game plan. I didn't know what their team philosophy was against me last year."
Bob Geren was the Mets bench coach last year and is the Dodgers bench coach this year. Seager said he will pick his brain to learn how the Mets attacked him. Seager said he appreciates that the club had the confidence to play him last postseason and he's eager for the second chance this fall. Although he's batting third, Seager said he doesn't think the club is asking too much of him.
"No, you want to be in there, you want to be in the big spots, in those moments," he said. "You're grateful they put you in there. You want to be the guy that helps the team win."
Which he has done beyond expectations. He finished in the league's top 10 for batting average (.308), hits (193), slugging percentage (.512), games played (157), runs scored (105), doubles (40) and extra-base hits (71). His 26 homers are the most ever by a Dodgers shortstop and he became just the fifth Dodger to post a 25-homer/40-double season.
Even the former MVP that lost his job to Seager has nothing but praise for the Dodgers' young superstar.
"Yes, he has definitely lived up to the hype and I'm happy for him, because he's a good kid first and foremost, respects the game, loves the game," said Jimmy Rollins. "He goes around the clubhouse like the typical rookie, from what I saw. He's quiet, you don't see him until you're in the dugout. And that's just respect for those who come before you. We can all attest that that doesn't happen a lot.
"I was kind of in that in-between stage, where I respected the elders but once the game started, I'm all over the place. It was like a concert. He's handled himself well, he's handled his rise well, and he's handled the LA lights well. I'm happy for him and he's had one [heck] of a season. He's going to have a great career, trust me."
Ken Gurnick is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.