No. 1 receivers key to Seahawks-49ers

Editor's note: Percy Harvin was ruled out of Sunday's game Friday afternoon.

Beyond the obvious ramifications of Sunday's matchup between the San Francisco 49ers and Seattle Seahawks -- Seattle can clinch the NFC West with a victory and San Francisco needs to win to keep hold of its wild card spot -- both teams will likely have their No. 1 receivers back. What difference will that make to their offenses? We tapped ESPN NFL Insider Matt Williamson to break down what Michael Crabtree and Percy Harvin bring to their respective teams.

Michael Crabtree, 49ers

SANTA CLARA, Calif. -- It took one game to judge the impact Crabtree can have on the San Francisco offense.

Crabtree, who is returning from a torn Achilles, had two catches for 68 yards (including a 60-yard catch-and-run) on 42 snaps in a 23-13 win over St. Louis. Crabtree's presence on the field enabled receiver Anquan Boldin and tight end Vernon Davis to get open. They combined for 13 catches for 180 yards. Most importantly, quarterback Colin Kaepernick, who has had to deal with a lack of weapons most of the season, looked comfortable and confident and he worked through his progressions because of the multiple options Crabtree's presence created.

It should only improve as Crabtree gets healthier down the stretch.

ESPN analyst Matt Williamson believes the biggest impact Crabtree will have is expanding the playbook of head coach Jim Harbaugh and offensive coordinator Greg Roman. Williamson believes the 49ers' have one of the most varied, deepest playbooks in the league. But without Crabtree, the team's play calling was hamstrung.

Williamson thinks he can see it become a factor as soon as Sunday. The Seahawks are missing cornerbacks Walter Thurmond and Brandon Browner.

"We could see the 49ers take advantage of that now,” Williamson said. "They can go with three receivers with Crabtree, Boldin and Manningham and Davis at tight end. Basically, that gives them four receivers. There have so many different packages that wasn't available that now are. It could give defenses problems that weren't happening without Crabtree.”

The 49ers have run 156 snaps in a three-receiver set. That is the fewest in the NFL. As a result, they have run 328 snaps with two tight ends. That is the sixth highest in the NFL.

Crabtree's return also deepens the receiver rotation. Fully healthy, Williamson thinks the 49ers' passing weapons are in this order: Crabtree, Davis, Boldin and Manningham. Crabtree's return could have a huge impact on Boldin.

Boldin goes from a No. 1 receiver to a No. 2 starter. If Crabtree and Davis are rolling, Boldin is going to get open often and it will cause major headaches for defenses. We saw that play out against St. Louis when Boldin had nine catches, his second most of the season.

Boldin will now be an important accessory to Crabtree, who was targeted on 34 percent of the 49ers' plays last season. It was the second highest rate in the league and Kaepernick has completed 67 percent of his career passes to Crabtree.

"I think we're just starting to see the impact of Crabtree in San Francisco,” Williamson said. "Kaepernick has his security blanket back.”

-- ESPN.com 49ers reporter Bill Williamson

Percy Harvin, Seahawks

RENTON, Wash. -- The 49ers didn't have to deal with Harvin earlier this year, not that it mattered. The Seahawks still won 29-3 at CenturyLink Field.

But San Francisco's defense and special teams may have to account for Harvin's skills on Sunday at Candlestick Park.

If all goes well at practice this week, a big if considering the unpredictable recovery for Harvin this season, he will play on the road for the first time this year.

Harvin made his season debut against Minnesota on Nov. 17 at Seattle, running back one kickoff 58 yards and coming up with a finger-tip reception on a 17-yard pass that kept a touchdown drive alive.

But soreness in his surgically-repaired hip caused him to miss the Monday night game against the Saints. Harvin had a cortisone shot last week to relieve inflammation. He hopes to play on Sunday.

ESPN analyst Matt Williamson sees Harvin as a special talent.

"I'm extremely high on him," Williamson said. "He's a very unique player and he's a lot more physical than people believe. You can line him up at so many different places. He does everything well. Versatility is his No. 1 asset.

"He's sure-handed and he's fantastic after the catch.”

Harvin was acquired from Minnesota in an offseason trade that sent the Vikings three Seattle draft picks -- a first-round and seventh-round pick in 2013 and a third-round choice in 2014.

Harvin signed a $67 million, six-year deal with the Seahawks, with $25 million guaranteed. But he injured his hip during the summer and has surgery Aug. 1 to repair a torn labrum. The usual recovery period for that type of surgery is four months.

Seahawks fans have only seen a glimpse of what he can do, but Seattle still is 11-1.

"It's not like they need another threat,” Williamson said. "But he's one more piece for an offense that's really clicking. He's one of those type of guys that you can line up anywhere on the field and the defense has to know where he is.

"You can't have a big linebacker cover him. He can line up in the slot and run a go-route. Wes Welker is not going to do that for you. You can't have press coverage against [Harvin] without a safety over the top or he will run right past you.”

Even without Harvin, the Seahawks have a strong receiving corps with Golden Tate, Doug Baldwin, Jermaine Kearse and tight end Zach Miller.

"People are so afraid of that [Seattle] running game that the receivers often get a lot of one-on-one situations,” Williamson said. "Then you have a quarterback (Russell Wilson) playing at a MVP level and putting the ball right where he needs to.”

Williamson believes Harvin's presence will make Seattle's offense more unpredictable.

"He's a competitive, nasty guy on the field who wants to win,” Williamson said. "You can throw it to him deep or throw it over the middle. He can run end around. He can line up in the backfield. I think they will hand it to him a few times.”

And he's also a dangerous return man, as he showed on his first attempt this season, taking a kickoff in the end zone and returning it up the middle 58 yards. The next time Harvin lined up for a return, the Vikings opted not to kick to him.

Now it's just a matter of Harvin getting 100 percent healthy. And no doubt the 49ers are planning what they need to do stop him.

-- ESPN.com Seahawks reporter Terry Blount