Although the nearest major event on the NFL calendar is the 2016 Scouting Combine next week in Indianapolis, Tuesday marked an official start of sorts to the league's free agency buildup – which will reach its zenith on March 9 (the first day teams can sign 2016 free agents).

Tuesday was the first day of a two-week window in which clubs can designate an impending free agent with either the franchise or transition tag. We mention that in this post because at least a few of the top free agents for 2016 will likely never actually reach free agency. Between now and March, teams will use the tags to stop their star players from signing elsewhere. In each of the last two years, six players have drawn the franchise or transition tags. Here is NFL.com’s list of players who could be candidates in 2016.

The franchise tag comes with two options: exclusive and non-exclusive. The former means a player can only negotiate with his current team, while the latter allows him to negotiate with other teams. The transition tag gives the team a right of first refusal if the player receives a contract offer elsewhere.

In regards to the franchise tag, if the two parties are unable to come to terms on a long-term contract, the player would get a one-year, guaranteed contract based on the average of the five largest prior-year salaries for players at that position. If you want to see what those figures could look like this year or simply want more information about the different tags, go here.

The 49ers have used the franchise tag on four occasions: for linebacker Julian Peterson in 2004 and 2005, for defensive tackle Aubrayo Franklin in 2010 and for safety Dashon Goldson in 2012.

San Francisco's list of unrestricted free agents in 2016 is comprised of wide receiver Anquan Boldin, guard Alex Boone, running back Reggie Bush, tight end Garrett Celek, kicker Phil Dawson and nose tackle Ian Williams.

With that preface out of the way, let's get to what you came here for: the top five free agent players at each position. We used Pro Football Focus’ rankings to determine the order.

According to Over the Cap, the 49ers will have the third-most salary cap room in 2016, so it seems likely the team will be an active player come March. Here are many of the names you should know beforehand.

Quarterbacks

Kirk Cousins, Washington Redskins

Sam Bradford, Philadelphia Eagles

Ryan Fitzpatrick, New York Jets

Brock Osweiler, Denver Broncos

Matt Hasselbeck, Indianapolis Colts

Running backs

Doug Martin, Tampa Bay Buccaneers

Lamar Miller, Miami Dolphins

Chris Ivory, New York Jets

Matt Forte, Chicago Bears

James Starks, Green Bay Packers

Wide receivers

Alshon Jeffery, Chicago Bears

Marvin Jones, Cincinnati Bengals

Rishard Matthews, Miami Dolphins

Travis Benjamin, Cleveland Browns

Jermaine Kearse, Seattle Seahawks

Tight ends

Antonio Gates, San Diego Chargers

Dwayne Allen, Indianpolis Colts

Ladarius Green, San Diego Chargers

Vernon Davis, Denver Broncos

Benjamin Watson, New Orleans Saints

Interior offensive line

Richie Incognito, Buffalo Bills

Evan Mathis, Denver Broncos

Brandon Brooks, Houston Texans

Ramon Foster, Pittsburgh Steelers

Stefen Wisniewski, Jacksonville Jaguars

Offensive tackles

Kelechi Osemele (G/T), Baltimore Ravens

Cordy Glenn, Buffalo Bills

Donald Penn, Oakland Raiders

Kelvin Beachum, Pittsburgh Steelers

Mitchell Schwartz, Cleveland Browns

Interior defensive line

Damon Harrison, New York Jets

Nick Fairley, St. Louis Rams

Ian Williams, San Francisco 49ers

Akiem Hicks, New England Patriots

Brandon Mebane, Seattle Seahawks

Defensive ends

Muhammad Wilkerson, New York Jets

Olivier Vernon, Miami Dolphins

Jason Pierre-Paul, New York Giants

Malik Jackson, Denver Broncos

Robert Ayers, New York Giants

Linebackers

Von Miller, Denver Broncos

Bruce Irvin, Seattle Seahawks

Danny Trevathan, Denver Broncos

Derrick Johnson, Kansas City Chiefs

Jerrell Freeman, Indianapolis Colts

Defensive backs

Josh Norman, Carolina Panthers

Eric Berry, Kansas City Chiefs

Eric Weddle, San Diego Chargers

Sean Smith, Kansas City Chiefs

George Iloka, Cincinnatti Bengals