SAN FRANCISCO (CBS SF) — San Francisco head coach Kyle Shanahan admitted Monday he was surprised to learn that back-up defensive end Damontre Moore suffered a season-ending fractured forearm sometime during the 49ers 37-8 victory over the Green Bay Packers.

Moore had recently rejoined the team after defensive tackle Ronald Blair went down with an torn ACL and was lost for the season. In the 49ers feel-good season, Moore may have been one of the team’s most heart-warming stories.

The veteran out of Texas A&M had bounced around the NFL for the last six years and joined San Francisco in training camp after the San Diego Fleet of the Alliance of American Football folded. He played well — recording four tackles and three quarterback hits in a pre-season game against Denver.

But he suffered a broken thumb and because was one of his veteran player’s status couldn’t be placed on the practice squad. The 49ers reluctantly cut him. He told reporters two weeks ago he couldn’t believe his luck being asked to join a team with such high post-season hopes.

At the time he received the call, Moore was babysitting his 5-month-old son at his Mansfield, Texas home.

Moore had one solo tackle and two assists in the 49ers win and gave no indication to coaches or the medical staff that he had been injured.

“I know he’s really down, he wanted to be a part of this for the rest of the year,” Shanahan told reporters on Monday. “Going on IR (injured reserve) is not like he disappears, but he won’t be able to go out there anymore. It was really cool how he played these two weeks.”

“He put everything on the line, doing everything he could to earn a job. What he’s done in these two weeks, coming right off the street, coming in at a high level,” the 49ers coach continued. “Getting a huge turnover for us the first week… I can’t tell you how impressed we were… We didn’t know that he had a broken forearm. He didn’t know, the guy never told anyone.”

Shanahan said it wasn’t until after the game when Moore walked into the training room and said he had a pain in his arm, that the injury was discovered.

“He knew that there was pain in there, but he kept playing,” the 49ers coach said. “After the game, he went in to get some guys to check it out and it was broken…To watch him on tape playing with that shows you he’s a special dude.”

Shanahan told reporters it was hard to see the exact play Moore was injured on.

“From what he told the trainers is it was the one that Aaron (Rogers, Green Bay quarterback) scrambled on and Richard Sherman was called for a penalty in the end zone,” he said.

The 49ers would elevate defensive lineman Jeremiah Valoaga from the practice squad to replace Moore.

“He was with us in training camp, he’s been on practice squad all year and is ready to go,” Shanahan said.