Ranking the NFC West Cornerback Groups

How do the 49ers' cornerbacks stack up?
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During the next two weeks, I will publish a series of articles in which I rank the 49ers position-by-position against the other three teams in the NFC West. Which team has the best running backs? Which team has the best wide receivers? And so on.

Today, let's rank the cornerbacks.

Depending on who you talk to, cornerback either is the most important position on a defense or the least important position, and there doesn't seem to be any in between.

How you feel about the cornerback position reveals your philosophy about pass defense in football. Either you feel cornerback is the most important position, he shuts down the opposing team's No. 1 target and gives the pass rush more time to hit the quarterback. Meaning a shutdown corner makes a mediocre pass rush good.

Or you believe a great pass rush speeds up the opposing quarterback, gives the secondary less time to cover and makes a mediocre secondary better. Those are the two different philosophies of pass defense. And each NFC West team has its own philosophy.

With that in mind, let's rank the NFC West cornerback groups from the worst to the best.

1. The 49ers

I know what you're saying -- the 49ers had the No. 1 pass defense in the NFL last season. How could their corners rank last in the NFC West? Fair point.

But this cornerback group basically is the same one that gave up 35 touchdown passes in 2018. So what changed? The pass rush. The 49ers added Nick Bosa and Dee Ford. 

And the underneath coverage in the zone defense changed -- the 49ers drafted Dre Greenlaw and signed Kwon Alexander, two of the fastest linebackers in the league. Suddenly, opponents had an extremely difficult time completing short passes against the 49ers, especially short passes to running backs. That's why their pass defense improved.

The 49ers use zone defense most of the time, meaning they believe cornerbacks are the least important players on the defense. I'll explain why with a baseball analogy. Think of the four underneath coverage players -- the linebackers and the strong safety -- as the infielders. They're all extremely important to the defense. And think of the three deep coverage players -- the free safety and two cornerbacks -- as the outfielders. The centerfielder is extremely important for the defense, but the corner outfielders aren't.

In zone coverage, the corners hide on the periphery. So the safeties and linebackers are more important. 

The Niners have skimped on corners the past two decades. Haven't drafted one before Round 3 since 2002, when they took Shawntae Spencer in Round 2. They put all their resources into the defensive line and try to find bargains at cornerback. And this strategy has worked for the most part.

The 49ers signed Richard Sherman after he tore his Achilles. He is the best zone cornerback in the league and the smartest corner of all time. In zone, the corner can stare at the quarterback -- he doesn't have to turn and chase a wide receiver. So the corner can read plays. And no one reads plays better than Sherman. Simply based on the alignments, formations and the initial route combinations, Sherman usually can figure out what's coming. 

The 49ers also have K'Waun Williams and Emmanuel Moseley, who both are solid in zone coverage. And the 49ers have Ahkello Witherspoon, who's shown flashes of excellence playing man-to-man coverage, but he's terribly playing zone. Gets lost all the time. Doesn't seem to be a good fit, but could be valuable to a different team with a different philosophy.

Here's the 49ers problem: They can't play zone coverage all the time. When they play the best offenses in the NFL -- the Chiefs, the Saints -- usually the game is close in the fourth quarter, and that's when defenses have to play some man coverage. Because if the game is close late, and there's a critical third and four, the defense can't just hang back in zone and concede a four-yard pass. The defense has to actually cover the receivers and take away the openings.

That's when the 49ers have gotten in trouble in the past. If an opponent can keep the game close in the fourth quarter, it can exploit Sherman, Williams, Moseley in man coverage during crucial plays. That's how the 49ers lost the Super Bowl.

And that's why I expected the 49ers would draft at least one corner this year, but they didn't. They drafted another defensive lineman instead, because the 49ers have a philosophy. The NFL is a salary-capped league, and corners and defensive linemen are the two most expensive positions on the defense. Can't have lots of expensive players at both positions. So the 49ers went all-in with their defensive line. Meaning they don't care if they have the worst corners in the division -- they still have the league's No. 1 pass defense.

2. The Cardinals

The Cardinals starting cornerbacks are Patrick Peterson and Byron Murphy. Both are former first-round picks. Murphy was a rookie last season and he struggled, but he's a talented player. Most NFL teams probably would rather have him than Moseley.

Peterson arguably was the best cornerback of the 2010s -- him or Sherman. Peterson missed six games last season and struggled at times, but he played behind a bad pass rush. The Cardinals defense ranked 17th in sacks last season. If you put Peterson on the 49ers, he would be great. So would Murphy. And if you put the 49ers cornerbacks on Arizona, they probably would struggle like they did in 2018 when the 49ers' pass rush was non-existent.

Peterson still is one of the most athletic cornerbacks in the NFL. He's elite in man-to-man coverage and zone. And most general managers, including John Lynch, probably would take Peterson over Sherman at this point in their careers.

3. The Seahawks

The Seahawks' pass rush was worse than the Cardinals' last season. The Seahawks ranked 28th out of 32 teams in sacks. Which means their corners had the toughest job of any corners in the NFC West.

And the Seahawks corners played well. Their No. 1 guy, Shaquill Griffin, broke up 13 passes and was equally effective in man coverage and zone. He's the kind of corner the 49ers don't have. The Seahawks mostly play zone coverage, but they've evolved recently to incorporate more man to man, because they lost a Super Bowl in 2015, and know it has become impossible to win a championship playing purely zone.

Their No. 2 corner is Tre Flowers, who intercepted three passes in 2019.

And then this offseason, the Seahawks traded a fifth-round pick to Washington for Quinton Dunbar, who intercepted four passes last season. Dunbar was recently arrested, but he plead not guilty, so we don't know if he'll play next season.

Even if Dunbar doesn't play, the Seahawks still will have two quality corners.

4. The Rams

The Rams have a totally different defensive philosophy than the 49ers. The Rams play man coverage. The 49ers play zone. Meaning the Rams take cornerback extremely seriously. For the Rams, it's the most important position on the defense.

That's why they traded for Jalen Ramsey, who probably is the best cornerback in the league. Most teams don't even throw his way. He's like a young Sherman who's more athletic. And the Rams No. 2 cornerback is Troy Hill, who intercepted two passes last season.

This is a competition the Rams want to win. They're worth nothing on defense if they don't have great corners, and the Rams know it. 

Just a difference of philosophies.