Borland has decided to retire because of concerns about the long-term effects of repetitive head trauma, ESPN reports. "I just honestly want to do what's best for my health," Borland said. "From what I've researched and what I've experienced, I don't think it's worth the risk."

Borland is just 24 and hasn't had major head trauma in the past few years, so he decided to retire solely based on concerns about his long-term health. He says he had just two diagnosed concussions, both before college, although he says he suffered a undiagnosed concussion last year in training camp that got him concerned over his health. Borland's retirement is a major blow to the 49ers' defense that saw Patrick Willis also retire last week.

With Patrick Willis' retirement, Borland is in line to start for the 49ers at middle linebacker in 2015.

Prior to Willis' retirement, there was concern regarding whether or not the rookie sensation would see regular playing time in 2015. Now that he is guaranteed a starting spot, Borland should be considered a lock (barring injury) for 100-plus tackles this season, making him an intriguing option in IDP leagues.

Borland (ankle) was placed on season-ending IR on Saturday, NFL.com reports.

Borland's ankle injury will cost him the last two games of his rookie season, but it was still a smashing success of a debut for the third-round pick, who showed the ability to pile up tackles at a rate faster than any other linebacker in the league. Unfortunately for his 2015 IDP prospects, NaVorro Bowman (knee) and Patrick Willis (toe) figure to reestablish themselves as starters in the offseason, health permitting.

Borland (ankle) is out fr Sunday's game against San Diego.

Borland's absence leaves the 49ers incredibly thin at inside linebacker, especially with Michael Wilhoite (hip) questionable. Nick Moody and Desmond Bishop are next in line.

Borland (ankle) didn't take part in practice Thursday, the 49ers' official site reports.

With two absences from practice in his back pocket this week, Borland's availability for Saturday's game against the Chargers is certainly in question. Alas, IDP owners still involved in the fantasy postseason should continue to watch his status closely, as he's averaged 12.9 tackles per game over the last seven contests.

Defensive coordinator Vic Fangio said Tuesday that "it would be a stretch right now" to expect Borland to play again this season.

Borland has tallied an astounding 102 tackles (79 solo) in eight games since Week 7, but his impressive rookie season may be over. Nick Moody is the favorite to replace Borland in the starting lineup, though Desmond Bishop -- who was just signed Tuesday -- could see some snaps in his place as well.

Borland collected six tackles (three solo) before having to exit Sunday's loss to the Seahawks with an apparent ankle injury.

Borland suffered the injury in the second half and tried to play through it, but was visibly limited and had to remove himself from the game. The severity of the injury is unknown, so it is tough to say whether or not Borland will be able to suit up this week against the Chargers.

Borland collected 14 tackles (12 solo) in Sunday's loss to the Raiders.

Borland continues to rack up the tackles at a tremendous clip. He didn't slow up after winning NFC Defensive Rookie of the Month in November, turning in another double-digit tackle performance to start the month of December. He doesn't get to the quarterback often, but owners aren't complaining so long as Borland continues to pile up tackles.

Borland racked up 16 tackles (all solo) in Thursday's loss to the Seahawks.

Borland was the lone bright spot for a 49ers team that failed to show up for its Thanksgiving matchup with the Seahawks. He led the team in tackles for the fifth consecutive week, and it was his fourth double-digit tackle performance through six starts this season. He has been an IDP machine since entering the starting lineup and should continue to be rolled out there on a weekly basis.

Borland tallied eight tackles (six solo) in Sunday's win over the Redskins.

Borland wasn't as impressive as he was last week when he won NFC's Defensive Player of the Week honors, but he still put together a solid effort. With a matchup against the run-heavy Seahawks on Thanksgiving, Borland should be a must-start in IDP leagues.

Borland (shoulder) had a monster game Sunday, leading the team with 13 tackles (nine solo) and nabbing two interceptions in the win over the Giants.

Borland entered the game with a minor shoulder injury, but it certainly didn't affect his performance on the field Sunday. He continues to be one of the biggest surprises in IDP leagues this season, tallying a ridiculous 48 combined tackles over the 49ers last three games. His biggest knock coming out of the draft was his inability to drop back in coverage, so the two interceptions were a positive sign. Patrick Willis (toe) has already been ruled out for the season and NaVorro Bowman's (knee) status remains murky, so Borland will continue to start for the remainder of the year.

Borland (shoulder) is listed as active for Sunday's game against the Giants.

With Patrick Willis out for the season, Borland will continue to play a key role in the 49ers' defense, and with 43 tackles over his last three games, the linebacker has established IDP relevance.

Borland (shoulder) is probable for Sunday's game against the Giants.

Now that he's cleared to play, Borland is a borderline must-start as an IDP. He has 43 tackles and a sack in his last three games.

Borland (shoulder) practiced in full Thursday, Matt Barrows of the Sacramento Bee reports.

One day removed from a capped practice, Borland is safe to deploy in IDP formats after all, especially due to his production -- 43 tackles (33 solo), one sack, and one fumble recovery -- in three starts for Patrick Willis (toe), who was placed on injured reserve Wednesday.

Borland (shoulder) was a limited participant in practice Wednesday, the 49ers' official site reports.

Borland has spelled Patrick Willis (toe) admirably in recent weeks, and the latter's placement on IR on Wednesday ensures continued IDP viability for Borland for the remainder of the season. Friday's injury report should confirm, one way or the other, whether Borland is likely to suit up Sunday against the Giants in New York.

Borland filled in for Patrick Willis (toe) on Sunday and recorded 17 tackles (11 solo) and a recovered fumble in the overtime win over New Orleans.

The rookie third-rounder continues to shine as a fill-in at middle linebacker over the past couple weeks. Willis' status for next week's game against the Giants won't become known until later in the week, but Borland is definitely worth an add in IDP leagues anyways. With 35 tackles in just a two-week span, he may find himself starting over Michael Wilhoite even if Willis returns.

Borland was a force on defense Sunday, racking up 18 tackles (15 solo) in the 13-10 loss to the Rams.

With Patrick Willis (toe) sitting out Sunday's contest, Borland stepped up and corralled the majority of St. Louis' ball carriers. He did missed a coverage assignment that led to the Rams' only touchdown of the game, but coverage isn't Borland's strength. Willis' injury isn't considered serious, but Borland will be worth an add if Willis can't go against New Orleans next week.

Borland led all 49ers with eight tackles (seven solo) and also recorded a sack in Sunday's loss to the Broncos.

Borland got the start in place of the injured Patrick Willis (toe) and produced similar statistics to the All-Pro linebacker. Willis' toe injury isn't considered serious, and he would likely make a return after the team's upcoming bye week. But is he were to miss any more time, then Borland would gain immediate IDP value.

Borland filled in for the injured Patrick Willis (toe) in the second half of Monday's game, recording two solo tackles in the win over the Rams.

Willis suffered a toe injury and was seen in a walking boot during the second half of Monday's game. The severity of the injury isn't known yet, but if Willis was forced to miss any time, then Borland would step in at middle linebacker Sunday against the Broncos.

Borland started Sunday's preseason game at middle linebacker and recorded five tackles in the 34-0 loss to Denver.

Borland has started the 49ers' first two preseason games in place of Patrick Willis, who is simply being given extra rest heading into the season. The third-round draft pick has received praise from the 49ers' coaching staff for his high motor, but has also received criticism for being too aggressive and missing assignments. Both of those assessments were proven correct Sunday when he was seen flying all over the field making tackles and stuffing lanes, but also missing a couple coverage assignments, one of which led to a touchdown for the Broncos. Borland is still a work in progress and will serve as a backup heading into the 2014 season.