The play in question came midway through the third quarter with the game tied at 3 and the Niners driving for a go-ahead score. Brock Purdy targeted Samuel on a slant over the middle on third-and-10 and hit him right in the hands.
But he dropped it instead, turning a potential touchdown into a field goal and leading to boos from the home crowd.
"I catch that ball, there's nothing there but the end zone," Samuel said. "At the end of the day, I gotta catch that rock."
Instead, it was part of another lackluster day for a player who has gone from an All-Pro in 2021 to an unproductive one this season. Samuel tried to explain why he has gained only 97 yards from scrimmage the previous four games when he posted: "Not struggling at all just not getting the ball!!!!!!!"
Samuel later deleted the post, but not after it caused a bit of a social media firestorm and called it a matter of frustration.
The Niners tried to get him involved early Thursday night with Purdy throwing to him on the first play only for it to get broken up. Samuel ended the night with three catches on seven targets for 16 yards and two rushes for 3 yards as he was held to less than 30 yards from scrimmage for a fifth straight game.
But it was the play in the third quarter that stings the most.
"That was a big one," coach Kyle Shanahan said. "Third down, and with Deebo's skillset, it was a shot and we didn't score on the play. Deebo clearly needs to catch that ball."
It was that type of game for the 49ers, who were held to their fewest yards (191) in a regular- season game in eight seasons under Shanahan and the fewest points since scoring three in Shanahan's debut in 2017.
"Not good enough," Shanahan said. "I thought we played good enough to win obviously on defense and special teams. But we didn't get enough done on offense."
There was plenty of blame to spread around. Both offenses struggled during heavy rain in the first half when there was a heavy downpour but the 49ers weren't any better when the conditions improved after halftime.
After settling for a field goal on their first drive of the third quarter, the 49ers stalled. Purdy couldn't connect on a deep shot to Samuel on the next drive that ended with a punt.
Then after falling behind 9-6, Purdy missed an open Ricky Pearsall on a deep throw with the Niners in Rams territory. Two plays later, his deep shot to Jauan Jennings was intercepted by Darious Williams in the end zone.
"Looking back on it, second-and-11, just be smart, try to check the ball down when I can't see where he is at," Purdy said. "So, just got to learn from it."
It was a rough night overall for Purdy, who was held to less than 160 yards passing for the third time in four games. He went 14 for 31 for 142 yards with the interception and failed to lead a single TD drive.
The Niners lost a game when they didn't allow a TD for the first time since 2007 and are all but eliminated from playoff contention.
"I just feel like I had a lot of plays left out there that I could have made for our team," Purdy said. "I thought the defense and special teams played so good. And that's what's hurting me is I just feel like I failed the team. I could have been better for our offense and we could have put up more points