For the life of me, I’ve never been able to figure out the actual differences between cornerbacks and safeties. Are there physical differences between the people who play the positions (i.e., is one faster, bigger, and/or stronger than the other)? Can players readily switch back and forth between the positions?
It’s pretty variable nowadays. At various times in the past, it was in vogue to have strong safeties heavier than cornerbacks. A lot of times, the strong safety was essentially an extra linebacker, especially on running downs, and 240-pounders were not uncommon at the position.
Free safeties traditionally were (and often still are) responsible for covering a lot of area behind the cornerbacks against the passing game, so footspeed and range was important. Free safeties, therefore, were roughly similar in weght to cornerbacks – though an ideal free safety would be somewhat taller and lankier than an average cornerback.
Keep in mind that a cornerbacks prime responsibility is to cover opposing wide receivers (or cover short to middle sideline routes if in zone defense). This is not usually true of safeties, whose prime role is to backup the linebackers (strong safety) or cornerbacks (free safety) if they get beat. When an offensive team brings in 3 or 4 wideouts, the defense normally counters with dropping linebackers and adding a 3rd and 4th cornerback, as opposed to just letting a safety cover any extra receiver.
Nowadays in the NFL, a lot of the traditional distinctions are blurred. Many defense don’t require a clear-cut physical distinction between a strong and free safety, so most pro safeties are now roughly the same size. More specifically, you no longer have 260-lb monsters like David Fulcher playing strong safety. Safeties still tend to be larger than cornerbacks, as agility and short-area quickness are more important in the latter than size. Additionally, you see safeties today often taking the prime responsibility for covering good pass-catching running backs or tight ends – especially when it’s a back like Marshall Faulk, who will run pass patterns downfield.
Bordelond makes most of the relevant points. One difference I would point out is that safeties are generally better tacklers and much harder ‘hitters’ than corners. There was a reason noone would throw at Deion Sanders’ side of the field but running backs usually went right at him - the man was a lousy tackler. A hard-hitting safety, meanwhile, can give receivers cause for thought if they’re running a crossing pattern and the receiver knows he’ll get crushed should a ball come his way.
Corners usually have better hands and pass-defense technique than a safety, the better to intercept a ball or at least bat one away from a receiver. A safety is more likely to just blast a receiver after they catch it.
Excellent site showing samples of individual NFL teams’ playbooks, complete with optional Shockwave graphics. I selected the following four snippets to show examples of how the roles of cornerbacks and safeties may vary:
Further reading about basic defensive sets used in football, also with Shockwave graphics. The roles of cornerbacks and safeties in each set are demonstrated in the graphics.
That is an incredible site, bordelond (and a nice cite, too!). Note that “defensive back” is the same thing as “cornerback” AFAIK.
Actually, the term “defensive backs” normally encompasses both safeties and the cornerbacks.
So-called because they’re on defense and they play back behind the line of scrimmage. (Unlike, um, the defensive line. ;))
–Cliffy