Each year, we like to run a series of posts called "90-in-90." The idea is that we'll take a look at every player on the roster, from the very bottom to the top and break them down a few ways. This roster will certainly change, and some days we'll have more than one so it's not exactly 90 players in 90 days. At this point, it's a name we're keeping around for street cred.

Once considered a top ten pick and one of the best defensive linemen in the 2013 draft, Cornellius "Tank" Carradine suffered an ACL tear in the middle of his final season at Florida State. Naturally, his draft stock went down, but the San Francisco 49ers took a shot on him, using one of their two second round picks in the 2013 NFL draft.

Carradine remained on the Reserve/NFI through the first six weeks of the 2013 season. On October 29, the 49ers added Carradine to the 53-man roster. On or about December 10, the 49ers placed Carradine on the Injured Reserve. Later we learned the young defensive tackle had to return to the operating room to clean out scar tissue known as arthrofibrosis.

Prior to his injury, Carradine was seen as the top 4-3 defensive end. Carradine has incredible size (6'4", 275 lbs.), but he is also incredibly fast. We all know he ran a 40 in 4.75 seconds, four months post-surgery. It is an impressive speed for a man of his size. But, here we are, over a year later. Where does Carradine stand?

There have been a myriad of writers who have praised Carradine and his pre-injury play, but we have little to gauge his actual abilities at this point in time. The good news is the second surgery has helped Carradine and by all appearances, he seems healthy. A few days ago, after getting his first look at Carradine on the field in pads, defensive coordinator Vic Fangio made some comments.

"He's getting better. He looks kind of like I thought he would," Fangio said on Sunday. "He's healthy, which is a good thing. He was never healthy last year and now he's getting a chance to learn and show what he can do mentally." "Sitting in those meetings doesn't mean you've learned it and he's living proof of that," Fangio said. "So he's got to do better from an assignment standpoint for us to feel comfortable to play him. Right now, he's missing too many things mentally."

It's not hard to get excited about what Carradine might bring to the defensive line once fully healed from his injury. Prior to the injury, he was very athletic, powerful, and violent on the field. Fangio is a forthright individual and isn't the type to sugar coat things. Fact is, Carradine is just now just getting on the field in a healthy state. Obviously, he has a lot to learn. And Fangio is a believer of on-field learning. He routinely speaks about the inferiority of learning in the classroom versus learning on the field.

Why he might improve:

As an end in a 4-3 in college, Carradine was a pass rusher and lined up on the outside shoulders of tackles. He was light on his feet and very fast. A quick tempo is a terrific asset for reducing the field, but can work against a player if he pursues at a bad angle and/or over-pursues the ball. Carradine has shown decent control and was able to rack up 80+ tackles. Carradine understands defensive fundamentals. His technique is not perfect, needs better read and diagnose skills; but, if the tackling foundation is there, he can be coached to read and diagnose faster and effectively.

If on the roster, 49ers most likely will work Carradine in slowly to give the starters a breather. The team is effective with the nickel formation and I can see Carradine plugged in easily to create an additional element of surprise. Linemen have to figure out where the fourth (or fifth) defender is coming from. Carradine offers the 49ers another dimension on defense.

Some have suggested the 49ers could move to the 4-3 due to the loss of Dorsey and with the personnel already in place. Granted, a defense can have components of both the 4-3 and the 3-4. And, the 49ers certainly do. The 3-4 base defense scheme incorporates some 4-3 gap control assignments. Not only does it make it a dangerous team to prepare for, but gives Carradine the opportunity to be a single gap penetrator and pass rush threat from the down lineman position. Carradine has the ability beat the offensive tackle around the corner with his speed or push back with a bull rush. It is good to see reports Carradine has gained some weight (now 296 lbs). Once he gets some experience, Carradine could prove to be a real impact player.

Why he might regress:

Even though the 49ers had Carradine on the active roster for approximately five weeks in 2013, his rookie season was effectively a redshirt year. The big question mark for Carradine has been his knee. It has been suggested he rushed his ACL recovery in an effort to gain exposure in the 2013 Draft. Regardless of the nature and extent of his rehabilitation, Carradine was forced to undergo a surgical procedure to clean out scar tissue in the knee.

Arthrofibrosis is a known complication after ACL reconstruction. Arthrofibrosis prevents a post-surgical patient from regaining full range of motion. Basically, the knee locks up. Carradine may not have realized there was a problem until after he actually practiced and could not get full extension of the knee. The problem with scar tissue is once it is present, there is a significant possibility the scar tissue will continue to accumulate. It can become a chronic condition. At the same time, in some cases (if the surgery is successful and he engages in proper rehab) scar tissue can be resolved completely.

Given that Carradine has not been placed on any injury lists and is fully participating in camp, it is a good indicator he is healthy. If there are no setbacks and his knee is free from scar tissue, his health should not be a factor.

Carradine's biggest challenge is he has not played in a football game since the date of his injury. It is no secret he is playing on one of the league's fastest moving, competitive defenses. As Fangio stated, Carradine is missing a lot mentally. It does not mean he cannot get there, but he will have to work hard every step of the way.

Odds of making roster:

With the loss of Glenn Dorsey and without the immediate return of Ian Williams, the 49ers will be forced to play a few more four-man fronts. Given the nature of the past schemes, pass rushers are key in those gaps. The 49ers will give every man a shot. Fortunately for Carradine, 49ers have two of the best positional coaches on defense. With Ed Donatell and Jim Tomsula, Carradine can make the progress necessary to get playing time. The preseason should give us more answers. If healthy, there is definitely a place on the roster for Carradine this year.