2015 NFL Free Agents: Riskiest Stars Worth Gambling on This Offseason

Although this year's NFL free-agent class is loaded with talent, not every team has the salary-cap space to splurge on a marquee name and thus franchises must be smarter with their money.

When money is tight, teams have to take a leap of faith. Sometimes it works out, in the case of Emmanuel Sanders to the Denver Broncos. Other times, it doesn't, such as with Toby Gerhart's disastrous first campaign with the Jacksonville Jaguars.

Anybody can say that adding Ndamukong Suh, Dez Bryant, Justin Houston or Darrelle Revis would be a smart move. It gets a little trickier when you look at the free agents below that top tier.

Among those players who have some major question marks, these three players should richly reward their next team.

Jake Locker, QB

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In his four NFL seasons, Jake Locker's played in 30 games, making 23 starts. To say that durability is an issue with Locker would be an understatement.

When he has been on the field, the 26-year-old hasn't exactly set the world ablaze, either. He's a career 57.5 percent passer, averaging 165.6 yards a game and boasting 27 career touchdowns to 22 interceptions.

Add in the fact that Locker was the eighth overall pick of the 2011 draft, three picks ahead of J.J. Watt, and it only adds to the disappointment. Even in a thin QB market, teams aren't exactly going to be banging down Locker's door.

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However, few will disagree that Locker still has physical tools to succeed in the NFL. He's mobile enough to escape the pocket and create more time, while his arm strength isn't in doubt.

Accuracy is a bit of an issue, with Locker himself acknowledging the problem in April 2014, per John Glennon of The Tennessean:

"

When we started off, not turning the football over played a huge factor in how we were able to start the season, so that's appealing and it's the most telling stat in football for a reason. So I want to continue doing that. And then (I want to work) on some fundamental things that will allow me to improve accuracy and completion percentage a little more.

"

Because of his injury history and lack of consistency, Locker's price tag won't be too high. He'd be a great fit for a team with an established starter in place and plenty of weapons in the passing game.

Somebody could do much worse at backup QB than Locker.

C.J. Spiller, RB

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C.J. Spiller is technically signed through 2015 with the Buffalo Bills, but it wouldn't be a surprise to see him opt out of his current contract:

On one hand, Spiller can be a home run threat any time he touches the ball. On the other, he's not really proven himself to be an every-down back. The most carries he's ever had in a single season is 207.

For comparison's sake, Jeremy Hill, whom the Cincinnati Bengals actively limited early in the season, carried the ball 222 times this year.

Spiller's yards-per-carry average has also dropped in each of the last three seasons, going from 6.0 in 2012 to 4.6 in 2013 and then 3.8 this past year.

In an age when running backs are both less valuable and more bountiful, why would a team shell out big money for the 27-year-old—especially one coming off a broken collarbone?

At his best, Spiller can be among the top RBs in the league. In 2012—Spiller's best season—Football Outsiders ranked him third in DYAR (Defense-adjusted Yards Above Replacement). Only Adrian Peterson and Marshawn Lynch rated higher.

Spiller then fell to 43rd the following year. However, a few different factors played into that decline.

First, Football Outsiders indicates the offensive line dropped from seventh in run-blocking in 2012 to 16th in 2013. That was also the year when Doug Marrone took over as head coach for Chan Gailey, which many saw as the moment Buffalo began struggling with how to properly use Spiller's skill set.

Marrone himself admitted that his motivation first and foremost was to win football games rather than cater to Spiller, which isn't necessarily an unreasonable thing to say, per Matthew Fairburn of Syracuse.com:

NFL.com's Chris Trapasso agreed that the Bills didn't maximize Spiller in the offense and added that the offensive line didn't help matters:

Bleacher Report's Cian Fahey concurred:

"

@MaRide1 Suspect it's more about the OL rather than the usage.

— Cian Fahey (@Cianaf) January 4, 2015"

In the right offense and with a capable line in front of him, Spiller can be a Pro Bowler once again.

Sean Weatherspoon, OLB

There's taking a chance on a player with injuries, and then there's signing a player who missed an entire season and nine games the season before due to health problems.

In 2013, a foot injury meant Sean Weatherspoon spent the majority of the season on the short-term injured reserve list. Then this past June, Weatherspoon ruptured his Achilles tendon and missed the entirety of the 2014 season.

When mostly healthy in 2011 and 2012, the 27-year-old linebacker recorded 220 total tackles, finishing second on the Falcons in tackles in both seasons. He also added seven sacks. While he didn't make a Pro Bowl, Weatherspoon established himself as a leader and key player in the Atlanta defense.

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You can't chalk all of the Falcons' defensive issues on Weatherspoon's injuries, but it's no coincidence that a previously strong unit in 2011 and 2012 really fell off in the following two seasons.

Here's a look at Atlanta's total yards allowed and DVOA (Defense-Adjusted Value Over Average) in the last four seasons:

In all likelihood, Weatherspoon will agree to a one-year deal, similar to the contract Brandon Spikes signed this past offseason.

The injuries obviously loom large, but at his best, plenty of teams could use Weatherspoon's services. Getting a player like that is well worth taking the short-term gamble.