Four games. Zero sacks. Are you kidding, 49ers?

At some point, you have to look at the number and ask the obvious question.Are you kidding me?Four games.Four victories.

And not a single sack allowed by the 49ers.Not one.How in the name of Bill Walsh is that even possible?In a league where defensive coordinators spend their waking hours figuring out how to wreck quarterbacks’ afternoons, the 49ers have gone an entire month without letting an opponent finish the job.Enjoy this while it lasts.History suggests you might wait a very long time to see it again.The 49ers are the first team since Peyton Manning’s 2005 Colts to open a season with four consecutive games without surrendering a sack.

They are just the fifth to do it since team sacks began being tracked in 1963.Twenty-one years between occurrences.“It starts with the O-Line, but collectively it’s been a huge deal and definitely wasn’t expecting to do that all the way up until now,” coach Kyle Shanahan said.When the man designing the offense is surprised, that tells you something.Nobody should expect that zero to survive an entire season.But the combination responsible for it should have the 49ers feeling awfully good about what comes next.Start with left tackle Trent Williams, left guard Connor Colby, center Jake Brendel, right guard Dominick Puni and right tackle Colton McKivitz.They are giving Brock Purdy time to operate and Shanahan room to work.General manager John Lynch sees the benefits of familiarity.“And all these guys have played a lot of football, but they got to play a lot of football together,” Lynch said Thursday during his weekly appearance on KNBR.That matters when five men must recognize and respond to trouble together.“I will acknowledge I think they’ve elevated their game and I think they’ll have to,” Lynch said.Purdy sees the work behind the improvement.“Yeah, they’re awesome.

Just how they come to work every single day, attacking meetings and practice and it just translates on Sundays,” he said.Williams has ...