When Kyle Shanahan expressed that the 49ers planned to be aggressive in free agency, many fans began to imagine the team improved by the acquisition of one or more edge rushers, a dominant single-high safety, or a dynamic wide receiver. As promised, the 49ers came to an agreement on a big deal on the first day of legal tampering. Surprisingly, that deal secured the services of a WILL linebacker, Kwon Alexander, formerly of the Tampa Bay Buccaneers. While the move, and the money assigned to the acquisition, puzzled many fans, the 49ers managed to replace the loss of former first-round pick Reuben Foster with a Pro Bowl alternate who is actually four months younger than Foster.

Foster's dismissal from the team left a unit that was low on talent in dire straits, and his trademark energy was absent from a team that needed leadership and enthusiasm. In Tampa Bay, Alexander was regarded as the enthusiastic soul of the defense, like Foster was with the 49ers. Unlike Foster, Alexander was regarded off the field as a mature, thoughtful man who was active in the community.

John Lynch and Kyle Shanahan like leaders on their roster, but they were not hired to assemble a community action team. The most vital aspect for determining Kwon Alexander's value to the team will be his play on the field, and he certainly has a lot to offer.

After grading some of his games from early 2018 (before he suffered a torn ACL), I want to break down what he has to offer to the 49ers defense, in the different responsibilities that can be assigned to a linebacker. It bears to point out that, due to the Buccaneers shifting their linebackers' alignments in response to motion, Alexander aligned both to the center of the offensive formation (like a Mike LB) and over the B gap, between the offensive tackle and guard (like a Will LB), so he has some flexibility. That said, Alexander will almost certainly play Will, lined up next to last season's star defensive rookie, Mike LB Fred Warner.

RUN DEFENSE

I saw two different players here, based upon his alignment. Alexander seemed more comfortable aligned like a Will LB (again, the position he's ideally suited for with the 49ers), as he was able to play in space with less complex run reads. At a Mike alignment, he appeared to occasionally guess at gaps and come up empty, and he was too easily reached by offensive linemen at the second level, which took him out of the play.

In a Will alignment, Alexander flew to the football, particularly on plays that tried to break wide and turn up the sideline. He's a blur in pursuit, and he appeared to be a much more secure tackle than his missed tackle numbers would suggest (more on that later). With two defensive linemen occupying the two offensive linemen to his side of the formation, he was free to use his athleticism to attack the football, and he produced some exciting hits on running backs who were trying to outflank him.

As a head up tackler, Alexander was more of a mixed bag. He tended to secure the back well enough, but, at 227 pounds, he lacks the mass to stop backs at the point of impact without getting driven for additional yards. As a trade-off for pure power, he seems to be one of those gifted defenders who can attack the football while securing a tackle, forcing six fumbles in just over three seasons of playing time.

COVERAGE

In my opinion, this is why Alexander was brought in. A cover three scheme can give up a lot of yards between the linebackers and the three deep zones, but a player with Alexander's range and versatility can make exploiting that space more dangerous for a defense. He displays the athleticism to blanket tight ends and to run with running backs out of the backfield in man coverage, though he occasionally got caught flat-footed by shiftier running backs running option routes off of him. He shows the awareness to close off throwing lanes and transition between targets in zone coverage, and he displays the aggressive physicality to strike receivers running into his zone, at times knocking them to the ground and wrecking a route package.

As a bonus, Alexander exhibits impressive ball skills and the courage to make a play on the ball when the safer move is to secure the tackle. In short, he is a playmaker in coverage.

BLITZING

I'm not sure I have mentioned this yet, but Kwon Alexander can run. His speed in coverage makes him a difficult defender for quarterbacks to throw at. As a blitzer, he often hits his gap before the offensive lineman assigned to the gap can disengage from a defensive lineman, allowing Alexander to get skinny through the gap and come free into the backfield. His agility allows him to adjust to the quarterback's attempt to escape the blitz, keeping the pressure on, and often forcing bad throws.

Alexander's one detriment as a blitzer is his apparent inability to disengage from a blocker when he fails to avoid contact, which leaves the secondary one man short and the pass rush no more productive than it would have been if he stayed in coverage. Those instances weren't the norm, however, as he frequently threatened the pocket with his speed when he blitzed.

MISSED TACKLES

I know that Alexander's missed tackles have been a huge focus on social media, but the numbers tell a bit of a misleading story. He misses tackles that most other linebackers can't even get to. Alexander's speed in pursuit allows him to close to sufficient range to attempt wild, diving tackles to stop backs and receivers from getting up the sideline.

At 6'1", with 30-inch arms, Alexander lacks the length to habitually bring down runners with flying arm tackles, but his failed attempts often divert the ball carrier's path, allowing pursuit from the rest of the team to catch up. Essentially, Alexander looks like a team player throwing his body around to benefit his squad, with little regard as to how the missed attempt will affect his stats.

ANOTHER ACL?

As much as the missed tackles seem like an empty concern, the ACL injury seems like a fair reason for caution. Advances in surgery and physical therapy make recovery from an ACL tear less of a gamble than in years past, but it bears to remember that Alexander suffered his injury in late October, and that the standard timetable for recovery could cause him to miss all of the offseason and some training camp practices. That's not ideal for a player joining a new defense at a position that relies so heavily upon reaction and instincts.

It is encouraging that Alexander posted video of himself squatting what appeared to be 315 pounds, but the real progress will occur once he starts changing direction and moving laterally, which could still be a way off.

BOTTOM LINE

The 49ers clearly believed they needed a pair of athletic, instinctive linebackers in the center of their defense, as that belief originally prompted them to select both Reuben Foster and Fred Warner in consecutive drafts. In Kwon Alexander, they get a young, athletic replacement for Foster who is a vocal and mature locker room presence. If (and it's a big "if") he can recover from his injury to resume his high level of play, and he can do so expediently enough to be familiar with the defense when the season starts, the 49ers will have secured the future at linebacker, with Alexander and Warner, for years to come.