Assessing Whether Dontae Johnson Can Start at Cornerback for the 49ers in 2015

Defensive losses have been the main storyline of free agency for the San Francisco 49ers and have severely affected their depth at the cornerback position.

In addition to losing linebackers Patrick Willis and Chris Borland to retirement and Dan Skuta to the Jacksonville Jaguars, the 49ers also saw cornerbacks Chris Culliver and Perrish Cox—both of whom excelled in 2014—depart for the Washington Redskins and Tennessee Titans, respectively.

San Francisco readdressed the balance somewhat with the signing of Shareece Wright. The Niners now have nine corners on the roster, but it is fair to assume that Marcus Cromartie, Leon McFadden and Cameron Fuller—signed as injury fill-ins last season—will not be on the active roster come Week 1.

That would leave Tramaine Brock and Dontae Johnson as the prospective starters, with Jimmie Ward and Wright competing for the nickel job ahead of Keith Reaser and Kenneth Acker, who effectively redshirted their rookie year due to injuries. 

There is of course the strong possibility the 49ers will elect to draft a corner in the early rounds this year, but with multiple needs at other positions, a future in which Brock and Johnson go up against opponents' best receivers seems to be on the horizon.

General manager Trent Baalke intimated as much when he recently insisted to reporters, prior to the signing of Wright, that he feels good about the Niners' cornerback depth (h/t Niners Nation):

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Feel good about it. Feel real good about it. We've got Tramaine Brock coming back. Dontae Johnson, a young guy that played well last year when he had the opportunity. Jimmie Ward coming back to play in the slot. We've got two guys that we drafted a year ago that weren't able to play - Keith Reaser and Kenneth Acker. We've got those guys in the mix. We're working on a couple of other things still, and then we've got a draft. I can see the thought process that you may have, but internally, feel good about the group and where it can go.

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Despite missing the majority of 2014 with a toe injury, Brock has previously demonstrated that he can be an effective starter in the NFL.

The more pressing questions will surround second-year player Johnson's capability to step up and deliver for a defense that ranked No. 5 against the pass last year but may struggle to recover from the loss of multiple key players.

The Rookie Season

The Niners waited until the fourth round to snag Johnson out of NC State, and it is not difficult to see what attracted San Francisco to him. At 6'2" and 200 pounds, he has the frame NFL teams are looking for in a cornerback and displayed athleticism at the 2014 combine by running the 40-yard dash in 4.45 seconds and recording a 38.5-inch vertical jump. 

Despite his physical gifts, there were many knocks on Johnson, the predominant issue being whether to play him at corner or safety. Furthermore, NFL.com's scouting report was critical of his top-end speed, inaccurate angles in pursuit and "ordinary" ball production.

With those concerns in mind, few would have anticipated Johnson's enjoying the year he did in 2014. Johnson played in all 16 games in 2014, starting three, and posted 34 tackles, six pass deflections and an interception returned for a touchdown—thoroughly decent numbers for a mid-round rookie.

According to Pro Football Focus, Johnson ranked at No. 51 among all corners in 2014 with a minus-1.7 grade, although that number was heavily influenced by his performance in the Week 17 game with the Arizona Cardinals, for which he received a minus-5.0 grade after allowing six of the 10 balls thrown his way to be caught for 107 yards and two touchdowns.

While that game was particularly ugly, Johnson did have some extremely promising showings. He allowed just three catches from seven targets in the season opener at the Dallas Cowboys, while Russell Wilson had a quarterback rating of just 48.8 when throwing at Johnson in the former Wolfpack defensive back's first pro start in Week 15, per PFF.

The numbers indicate that Johnson has plenty of potential but also much to improve on. With respected defensive backs coach Tim Lewis managing the secondary, the Niners can afford to be hopeful over Johnson's future.

Still, a greater breakdown of his play is required in order to get a true sense of whether he is starter material in 2015.

Film Study

Those worried about Johnson's long speed should look to his performance in the Week 15 game against Seattle in which he produced a demonstration of the promise he possesses as a potential starting NFL corner.

Take this play, where he is matched up against Jermaine Kearse—Seattle's best deep threat prior to the acquisition of Jimmy Graham this offseason:

NFL.com

Johnson stays step-for-step with Kearse and, despite a good throw from Russell Wilson, does enough to prevent the receiver from making the catch for a big gain.

It was not just Kearse who was left frustrated in that game, though, as Johnson also prevented tight end Luke Willson from making a big play:

NFL.com

After Wilson avoids pressure from Aldon Smith, Willson attempts to beat Johnson with a second move. However, Johnson stays aware, and although he doesn't get his head turned, he avoids a pass-interference call by making a play on the ball to ensure Seattle does not move the chains on third down. 

Ball skills were a concern surrounding Johnson heading into the draft, but in that previous play and in Week 6 at St. Louis, he demonstrated that he can make an impact in that area of the game.

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Here, Johnson once again shows good instincts by reacting to a poor decision from Austin Davis to throw the ball to Kenny Britt. He gets a terrific drive on the ball, makes the catch and is in the end zone in the blink of an eye, capping a 31-17 win for the Niners. 

But for all the positives of his rookie season, there was clear evidence of the weaknesses in his game, which were exposed in the two touchdowns he gave up in the season finale with Arizona. 

NFL.com

On Arizona's first score, Johnson shows his inexperience as a pro starter. He is easily fooled by the flea-flicker by Ryan Lindley, selling out to the run and allowing a good receiver, Michael Floyd, to get open for an easy touchdown catch.

Floyd again takes advantage of Johnson late in the second quarter to snag a second touchdown reception.

NFL.com

This time Floyd fakes inside, which is enough to confuse the raw Johnson, who affords him enough space to make the grab, accelerate clear and run the ball in for six.

The two scores Johnson gave up did not prove costly in the end, as the 49ers pulled out a 20-17 win, but such mental mistakes justify some doubt over his ability to slot right in as the starter in 2015.

Yet there is a lot to like about Johnson. He has all the physical traits you look for in a modern-day NFL cornerback, and on film, the supposed lack of top-end speed does not appear to be too much of an issue. Furthermore, he has the versatility to operate in the slot and has somewhat allayed fears over his ball skills.

The challenge for new secondary coach Lewis will be to iron out the kinks in Johnson's game that allowed wideouts like Floyd to enjoy big days against him. If he can do that, Johnson could develop into one of the better young corners in the league.

However, given the lack of quality depth in the 49ers secondary, it would be unwise to bet everything on a player who still has plenty of improvements to make in a season where there is likely to be plenty of pressure on the defense.

Nicholas McGee is a San Francisco 49ers Featured Columnist based in Leeds, England. Follow him on Twitter @nicholasmcgee24.