49ers defense may not have star end Nick Bosa for Week 1, and Earl Thomas will not be signed

A big reason the San Francisco 49ers' defense was one of the best in the NFL last season and helped the team reach the Super Bowl for the first time since 2012 was the selection of Nick Bosa at No. 2 overall in the NFL Draft. The former Ohio State star more than lived up to expectations in winning Defensive Rookie of the Year honors, and Bosa is a +900 second-favorite at William Hill sportsbook to win Defensive Player of the Year for 2020. However, an injury may delay the start of his season.

Bosa is being called week-to-week with a muscle strain in his leg – there are likely going to be a lot of these types of injuries around the league because there were no offseason activities due to the coronavirus. The strain was discovered by an MRI after Bosa had complained of soreness in his legs.

"Glad he ended up getting that MRI because there was more to it. … Fortunately, we caught that and we were able to prevent him from hurting it worse," coach Kyle Shanahan said to the media covering the 49ers.

Pro Football Focus ranks Bosa as the No. 7 edge defender in the league entering 2020. San Francisco opens Sept. 13 at home vs. Arizona with the Niners currently as 7-point favorites on the NFL odds. That spread shouldn't change even if Bosa sits, barring major action on the Cardinals. He wasn't a huge factor in San Francisco's season sweep over Arizona last year, totaling four tackles and no sacks.

Meanwhile, SportsLine oddsmakers earlier this week listed the 49ers as among the favorites to sign seven-time Pro Bowl safety Earl Thomas after he was released by the Baltimore Ravens on Sunday.

The Niners made sense as a landing spot as Thomas could reunite with former Seahawks Legion of Boom teammate Richard Sherman. However, Shanahan says the Niners aren't interested in Thomas and comfortable with their starting safety duo of Jaquiski Tartt and Jimmie Ward. The club also added veteran Johnathan Cyprien last week.

"I'm real happy with our safeties," Shanahan said. "Nothing against Earl, but there wasn't interest just because we have our team."

Needless to say, injuries or COVID-19 issues could change Shanahan's mind. Dallas, New England and Cleveland are the favorites for Thomas. Atlanta coach Dan Quinn has said his team isn't interested in Thomas, and the Falcons also had been among the favorites. 

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