49ers rookie Chris Borland retires

Standout linebacker Chris Borland told the San Francisco 49ers he is retiring.

Borland told ESPN’s ‘‘Outside the Lines’’ earlier Monday that he is leaving the game following his standout rookie season because of concerns about head trauma.

The 24-year-old Borland had a team-leading 108 tackles in his stellar rookie season, emerging as a punishing defender. He also had a sack and two interceptions.

He told ‘‘Outside the Lines’’ on Monday he wants to do ‘‘what’s best for my health.’’

“I feel largely the same, as sharp as I’ve ever been. For me, it’s wanting to be proactive,” said Borland, a third-round pick out of Wisconsin. “I’m concerned that if you wait till you have symptoms, it’s too late. . . . There are a lot of unknowns.”

This is yet another blow to the team that lost coach Jim Harbaugh after the season, then watched Frank Gore, Mike Iupati, Chris Culliver, and Perrish Cox depart in free agency this past week.

‘‘While unexpected, we certainly respect Chris’ decision,’’ 49ers general manager Trent Baalke said. ‘‘From speaking with Chris, it was evident that he had put a great deal of thought into this decision. He was a consummate professional from Day one and a very well-respected member of our team and community.’’

Borland’s announcement comes less than a week after the 49ers’ five-time All Pro linebacker Patrick Willis walked away from football.

Tebow visits Eagles

Tebow Time in Philly?

Tim Tebow worked out Monday for the Philadelphia Eagles, two people familiar with the session told The Associated Press. Both people spoke on condition of anonymity because the workout was not made public. One of the sources said Tebow worked out at quarterback and left the facility without discussing a contract.

Considering all the offseason moves made by coach Chip Kelly, taking a look at the 2007 Heisman Trophy winner with the huge following shouldn’t be a surprise. Tebow could run zone-read plays better than Philadelphia’s four current quarterbacks.

Tebow has not been on an NFL team since the 2012 season. He was released by the Jets, then attended training camp in 2013 with the Patriots, who cut him.

Tebow started 14 games for Denver over two years after being selected in the first round of the 2010 draft. He won a playoff game with the Broncos, who traded him for a fourth-round pick when they signed Peyton Manning.

Tebow has been working in television as an analyst for the SEC Network and ESPN.

Kelly recently traded starting quarterback Nick Foles to St. Louis for Sam Bradford. His backup is Mark Sanchez, with Matt Barkley and G.J. Kinne also on the roster.

Browns shore up DThe Browns began the second week of free agency by plugging two holes opened in Week 1. Cleveland signed cornerback Tramon Williams and defensive lineman Randy Starks, additions to offset the losses of cornerback Buster Skrine and pass rusher Jabaal Sheard — two recent free agency defections. . . . The Texans signed former Jaguars receiver Cecil Shorts III to a two-year deal worth $6 million, according to reports. . . . Former 49ers defensive lineman Ray McDonald filed a defamation lawsuit against a woman accusing him of rape. McDonald said security camera footage will show a consensual sexual encounter occurred in his hot tub. The 49ers cut McDonald in December after learning of the allegation. The Santa Clara County district attorney is considering whether to file criminal charges.

Raiders cut Schaub

The Raiders released Matt Schaub less than one year after acquiring him to be their starting quarterback. Schaub was beaten out for the starting job by rookie Derek Carr last year and was released Monday, just days after Oakland signed Christian Ponder as a backup. Schaub threw just 10 passes in his one season with the Raiders with two interceptions . . . Veteran guard Vladimir Ducasse agreed to a one-year contract with the Bears. The former UMass standout has made 11 starts and played in 63 games over five seasons with the Jets and Vikings.

Veteran safety Kurt Coleman signed a two-year contract with the Panthers, the team announced . . . Safety Jeron Johnson signed with the Redskins after four seasons as a backup with Seattle.