After tearing his Achilles, getting cut by the Seahawks, and landing in San Francisco, Richard Sherman, formerly the loudest and best cornerback in football, is piecing together another dominant season that has largely gone unnoticed as the 49ers stumble through a wasted season without Jimmy Garoppolo. Through six weeks, Sherman has quietly been one of the league's best cornerbacks. 

Remember when Aaron Rodgers and the Packers ignored Sherman's side of the field back during Sherman's prime? That sort of thing is happening again, this time in San Francisco.

As the San Francisco Chronicle's Eric Branch noted on Thursday, Sherman has allowed only 28 passing yards in coverage because he's been targeted only 10 times and has allowed two completions all season long -- two completions for 28 yards in five games.

The numbers Branch cited in his story come courtesy of Pro Football Focus, which provided more stats to highlight Sherman's effectiveness this season. So far this season, he's allowed the lowest passer rating in coverage and the fewest yards per snap in coverage.

Reminder: Sherman is 30 years old and he's coming off the kind of injury that can usually wreck a career. It's also a reminder that interceptions aren't the only way to judge and rank cornerbacks. That's not to say that Sherman is currently the league's best cornerback. But Sherman deserves credit for shutting down his side of the field. He's still effective.

The only problem? The 49ers are allowing 279 passing yards per game, which ranks 25th. It's a heck of a lot easier for opposing offenses to ignore Sherman's side of the field when they can pick on Ahkello Witherspoon, Jimmie Ward or Greg Mabin on the other side of the field. And that is a reminder that for all of the hype the 49ers generated entering the season -- largely because of Garoppolo's presence -- the 49ers still have a few weaknesses on their roster. The Sherman signing ended up being a good one for general manager John Lynch, but he still has some building to do, especially if the 49ers are going to overcome a team like the Rams in the NFC West.

Sherman is under contract through the 2020 season, but the 49ers can get out of that contract at any point without suffering severe financial consequences. Based on Sherman's level of play this season, the 49ers have no reason to move on from him. They should be building a secondary around him while simultaneously preparing for their long-term future, which probably doesn't include Sherman given his age.