Technically, the 49ers are 3.5-point underdogs this week against the Lions.

But the gap between these two teams is greater than 3.5 points. The Lions have outscored their opponents by 194 points this season while the 49ers have been outscored by 18.

On Saturday, I asked Kyle Shanahan to identify the biggest challenge the Lions pose to the 49ers.

“Just how good they are in all phases,” Shanahan said. “Their offense, everyone is well aware of how good they’ve been these last couple years. Anytime you have an O-Line as good as them, the running back as good as them, you can control the ball which takes a lot of pressure off the quarterback and on pass protections. And then when you have a quarterback as good as him with how accurate he is, with that O-Line and those receivers, they’re pretty lethal there.

“And then the defense, I know they’ve battled through a lot of injuries, but their secondary is as good as there is. They’ve been able to stay healthy there. They’ve lost one big one, but they have some depth there. And what they can create with their pressures and things like that because of their man coverage makes them very tough to be consistent with. They put a lot of pressure on you where they know how to stop the run with their scheme. And then you’re never going to get really many freebies. You’ve got to beat man coverage, you’ve got to beat pressures, which is going to always be hit or miss. But when you do that with an offense that’s so automatic it puts pressure on both sides of the ball to not let them lap you. So, you’ve got to be consistent, got to get turnovers.”

MY TAKE: It’s interesting that the first thing Shanahan mentioned was Detroit’s offensive line. Clearly, Shanahan understands the impact an elite offensive line can have on a quarterback. Maybe that means he finally will invest heavily in his own offensive line this offseason.

MY SECOND TAKE: Sounds like the Lions have shown Shanahan and the 49ers that you don’t have to invest heavily in the defensive line to create pressure and stop the run. As long as you have excellent defensive backs who can cover man to man, you can blitz and create pressure that way.

Maybe the 49ers finally will shift their focus from the defensive line to the offensive line this offseason.