No matter how few pass attempts the 49ers needed from Jimmy Garoppolo in the playoffs to still reach the Super Bowl, football is a passing man's game. Defending the pass is key to a successful defense and the 49ers were dominant at it last season.
The 49ers led all of the NFL by allowing only 169.2 passing yards per game last season, ranking just ahead of the New England Patriots (180.4). But San Francisco did allow 23 passing touchdowns and only had 12 interceptions. The Patriots, on the other hand, intercepted 25 passes and allowed just 13 passing touchdowns.
San Francisco and New England easily were the top two defenses by coverage last season. But when it comes to the cornerbacks, which team is the top dog? Pro Football Focus has the Patriots as having the top cornerback trio in the league, with the 49ers right behind them. The 49ers certainly still have a case.
It all starts with Richard Sherman. The 32-year-old still is elite. In fact, his 90.1 PFF individual coverage grade was the highest in the NFL last season. In his ninth season, he allowed one touchdown reception on 549 coverage snaps.
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On the opposite side of Sherman is Emmanuel Moseley, who emerged late in the season and took over for Ahkello Witherspoon. Moseley earned a 68.0 PFF coverage grade on the year, which was a top-50 grade among corners. He also had the 20th-ranked coverage grade (74.8) on passes thrown in three seconds or less. Despite only starting nine games, Moseley was credited with eight passes defensed.
And then there's K'Waun Williams, who might be the 49ers' most underappreciated player. The 49ers' nickelback had a 76.5 coverage grade as an inside defender, the seventh-best among the NFL's 47 qualifying slot defenders, according to PFF. Williams, simply, was a menace for opposing offenses.
Williams, 28, led the 49ers in forced fumbles with four last season and was tied for second with two interceptions. He only allowed one touchdown pass all last season, including the playoffs. In coverage and as a tackler in the open field, Williams was a star.
Overall, this trio of Sherman, Moseley and Williams combined for an 89.2 coverage grade, per PFF. Defense is a team effort, but the 49ers allowing an NFL-best 9.7 yards per reception shows how stifling this threesome can be. It should come as no surprise that San Francisco also gave up the least amount of explosive receiving plays.
The 49ers and Patriots each have one dominant cornerback on the outside. Sherman is San Francisco's guy, while Stephon Gilmore leads the way for New England. These two teams also have strong No. 2 corners and great slot defenders. Moseley's emergence is what could put the 49ers over the top.
Even when Moseley wasn't starting games, he was being inserted into critical moments. Then, he earned his start in the NFC Championship Game and took advantage of the opportunity. Moseley played 100 percent of defensive snaps in the win, and his interception of Aaron Rodgers with one minute remaining in the first half led to Raheem Mostert's third touchdown.
Sherman is a star, that isn't going to change. Williams needs to be seen as one of the best nickelbacks in football, and is due a big paycheck in the near future. If Moseley can continue to grow, though, the 49ers can leap the Patriots as the best cornerback trio in the game.