Eleven defensive players are responsible for limiting the opponent’s offense in football.
Two of these eleven players occupy “safety” positions: one free safety and one strong safety.
In this article, I will compare and contrast the two safety positions and identify those traits that all elite safeties must possess.
- Free and strong safeties differ significantly in many categories: physical size, defensive responsibilities, and positioning on the field.
- The most salient difference between the two positions is that strong safeties perform a much more significant role in run defense, while free safeties excel in pass defense.
- Despite their differences, elite players in both positions must possess similar physical attributes.
Free Safety vs Strong Safety
Free and strong safeties diverge in a litany of categories: physical size, defensive responsibilities, and positioning on the field. In simple defensive responsibilities, the clear distinction is that strong safeties must stop the run, while free safeties must stop the pass.
Related reading: WHAT IS A FORWARD PASS IN FOOTBALL? (DEFINITION & RULES)
Nevertheless, they are strikingly similar concerning skill sets which I covered more in-depth below. 
Since strong safety plays a significant role in run defense, he must be strong enough to shed blockers and tackle ball carriers.
As a result, strong safety is usually larger than free safety.
The free safety must cover significant distances to break up passing plays over the deep middle of the field and is often the fastest and most agile player on the defense.
Such tasks place a premium on the speed at the expense of size.
Strong safety’s primary responsibility is to provide support against the run.
Nevertheless, the strong safety typically covers the running back or the tight end in man coverage on pass plays.
In contrast, the free safety’s primary role is to provide zone support against the pass, meaning that the free safety often roams the deep middle portion of the field, attempting to break up any passes thrown his way.
Free safety is the deepest defender on the field and serves as the last line of defense.
The free safety must keep all plays in front of him; failure to do so will invariably result in a touchdown for the offense.
The strong safety earns his name due to his positioning on the field.
The strong safety lines up on the strong side of the field (the strong side is either where the tight end lines up (if there is only one tight end) or the side of the field that is the same as the quarterback’s handedness (if there is one tight end on each side). 
In contrast, the free safety lines up on the opposite side of the field as the strong safety – the weak side.
In terms of depth, the strong safety typically lines up much closer to the line of scrimmage than the free safety, as the free safety is frequently fifteen yards from the line of scrimmage. 
The picture below helps to illustrate the positioning:
While their responsibilities deviate, there is significant overlap in the skills required to play either safety position at an elite level.
The differences between free and strong safety have begun to blur over the past few years, with both players needing to excel at coverage and run suppression.
Pro scouts identify the most salient traits of elite safeties:
Instincts (quick and accurate first step): when playing free and strong safety, the first step is the most important. The player must quickly and accurately read pass or run and make his first move to stop the play.
A wrong read will leave him out of position to make a play, which usually results in big yards or points for the offense.
While speed and fluidity of motion are essential, all the speed in the world cannot cover up for a safety that cannot quickly and correctly diagnose a play.
Speed and acceleration: more than any other defender, safeties constantly move toward the ball, and they must traverse greater distances than anyone else on the team to get there.
That isn’t to say that all elite safeties are speedsters; however, those who lack great speed must compensate with quick and accurate first steps.
Nevertheless, the best safeties in the game possess a combination of instincts and athletic ability.
Agility: elite safeties must be able to stop on a dime and reverse direction with minimal deceleration. They must be agile enough to turn their hips and run with receivers when they make cuts in their routes.
Tackling: as the last line of defense, the safety must be willing to tackle, and he must be good at it. Little else matters if the ball carrier cannot be brought down.