Garoppolo represents hurdle to Jags’ surge

In three games since he was named San Francisco’s starting quarterback, Jimmy Garoppolo has shown a strong arm, good poise and an ability to improve an entire organization’s morale. Imagine what he could do when he fully grasps the offense. Still learning a new team and a new system, Garoppolo will face the toughest challenge of his young 49ers career when the Jaguars visit San Francisco today.

“We’ve got a good thing going,” Garoppolo said. “We’ve got a little bit of momentum with us, but it will be a good test this week. We’re looking forward to it.”

San Francisco had little, if anything, to look forward to this season until Garoppolo was acquired Oct. 30 (a day before the trade deadline) in what could become a franchise-altering move. The 49ers happily shipped a 2018 second-round pick to New England for the 26-year-old Garoppolo, who spent the previous three seasons learning under Tom Brady.

Garoppolo looked like the five-time Super Bowl champion last week when he led a fourth-quarter comeback to knock off Tennessee. Trailing 23-22 with 1:07 remaining, Garoppolo completed 3 of 4 passes (not including a spike to stop the clock) for 45 yards to move the 49ers into position to make a gamewinning 45-yard field goal as time expired. It was the last of three fourth-quarter scoring drives for the 49ers. And because of it, Garoppolo became the first quarterback to win his first five NFL starts — he has beaten Chicago, Houston and Tennessee while with San Francisco — since Pittsburgh’s Ben Roethlisberger in 2004.

Garoppolo is averaging 336 passing yards per game as a starter this season and has thrown three touchdowns against two interceptions with the 49ers. More importantly, the win over Tennessee continued to energize a team that has a lot of juice despite its 4-10 record.

“Our guys are excited. Our organization is happy,” firstyear 49ers coach Kyle Shanahan said. “We’ve only lost one game here the last five weeks.”

It also could be significantly more difficult to continue while facing a defense that leads the league in scoring (14.9 points per game) and passing (168.9 yards).

A Jaguars win or a Titans loss today clinches the AFC South for Jacksonville.