It is a self-evident truth that in this particular NFL season, offense has ruled the day. Quarterbacks are racking up yards at rates heretofore unmatched. Drew Brees is well on his way to shattering Dan Marino's single-season yardage mark this year after coming within fifteen yards of it in 2008. This may be partially due to a greater emphasis on the passing attack and the growing popularity of the spread offense (see: Buffalo Bills) but much of it this year has resulted simply from poor tackling and a lack of defensive fundamentals. I wrote a comment about this in a recent thread, but the subject intrigued me enough that I decided to do some research into the topic and share my findings with you. Here is what I have found.
It is a well-known fact that most cornerbacks are shorter than the receivers they cover. Why is this? We may speculate that these are simply fast players with good ball skills who have similar frames to wide receivers, but if they were taller they would in fact have become wide receivers. The average height of a cornerback is around 5'11". The best cornerbacks are closer to 6'1", but there are few of those. The average weight of a cornerback is around 200. Cornerbacks are expected to run at least a 4.5 forty. If they do not, they will be limited in the scheme and may be moved to safety.
Therein lies an issue. You have a lot of defensive players playing out of position at safety who do not fit the Ronnie Lott/John Lynch/Ed Reed ideal. These players are often too slow and don't like to hit because they are used to playing cornerback, a position in which too much physicality is penalized. This means the only guys actually fast enough to catch wide receivers are cornerbacks, and they are not considered the most solid tacklers. Deion Sanders reportedly ran a 3.9 forty in high school, but was not a good tackler. Sanders is considered the greatest cornerback of all time.
Your average NFL wide receiver is 6'1" and weighs around 200 pounds. They are expected to run at least a 4.4. If they do not, they are labeled a "possession receiver" and are limited to the slot. Let's take an Oakland receiver here for an example of what I am talking about. Darrius Heyward-Bey is 6'2" and 210 pounds. He ran a 4.3 40 time. That's insanely fast. He is considerably larger, heavier, and faster than the defenders expected to cover him. Receivers like DHB are becoming more and more common as time goes along- Calvin Johnson, Andre Johnson, Mike Wallace, and Larry Fitzgerald are also prime examples of the new standard for wide receivers. They are, on average, two to three inches taller, fifteen pounds heavier, and considerably faster than their defensive counterparts.
I feel the need to point out here that the greatest receiver of all time, Jerry Rice, ran a 4.6 40 time and that caused him to slide in the draft. However, Rice had the best hands and catching ability ever, as well as two Hall of Famers throwing him the ball in Joe Montana and Steve Young. Also, Rice was drafted in 1985 and many things have changed in the 26 years since his selection.
What has changed? Firstly, the boom in the popularity of football and sports in general has caused an industrial focus on producing better athletes through the avenues of nutrition and training. The advent of the Nautilus machine, which allows players to train with weights without a spotter, as well as the widespread use of nutritonal supplements and a greater understanding of what foods help football players do specific things well, have assisted in making all football players bigger, stronger, faster, and quicker.
The great Jim Brown was 6'2" and 232 pounds. The NFL had never seen anything remotely like him. He was able to outrun and bowl over most defenders of his day. Jim Brown was about the size of today's backup inside linebackers- guys who are too 'undersized' to start. The largest offensive lineman in 1979, the Bengals' Max Montoya, was 285 pounds. Today, Montoya would be so undersized at guard that he would be destroyed by the 300+ pound linemen he'd be trying to block. Randy White of the Cowboys played defensive tackle at 257 pounds. Today, he would be tossed around like a rag doll.
The position where players have changed the least amount is runningback. The clear reason for this is that with too large a frame, runningbacks will take too much punishment and be injured (see: Brandon Jacobs). However, the position has changed in that the men attempting to tackle said runningbacks have become steadily larger, stronger, and faster over the years. The best way for a runningback to avoid taking a pounding and suffer an injury is for them to not get tackled at all. Therefore, the ideal for the position has changed from a bruiser like Jim Brown to a combination of blazing speed, medium size and extreme elusiveness like Barry Sanders. The players who best combine Brown and Sanders' traits (Darren McFadden, Adrian Peterson, Arian Foster) are considered elite backs.
So what does this mean for tackling? It means that defenders are dealing with ball-carriers who intend to and are completely able to elude capture and outrun defensive pursuit. When the defense is practicing on one part of the field how to tackle ball-carriers, the offensive skills players are practicing how to avoid being tackled. This has always happened, the difference now is that this country has bred players who are able to avoid being brought down on an incredibly consistent basis. What it has not done is instill a sense of discipline into its youth. Football is a game of discipline, but that is most evident in the art of tackling. A defender must get himself into an advantageous position and then use technique and leverage to tackle a ball-carrier. Many times I have seen a would-be tackler simply hit the offensive player as hard as possible and then hope the player falls down. This may have worked in high school, it may have worked in college when the defender was the biggest and baddest guy around, but that will not work in an NFL where the offensive players are bigger, stronger, faster, and have better balance than the defenders. Discipline is the only way in the NFL for a smaller, weaker defender to bring down an athletically superior ball-carrier. When an NFL defender relies solely on his athleticism to make a tackle, he will oftentimes fail.
Linebackers are also expected to tackle, but linebackers are usually much slower than the men they are attempting to cover or stop. A quick glance at the upcoming NFL draft lists exactly one outside linebacker who runs 4.4 or lower, Zach Brown of North Carolina. Because of his elite speed he will likely go in the top half of Round 1. However, he is the only guy I can see who will be able to keep up with the ball-carriers running 4.4 and under. To tackle guys faster than you takes technique and discipline. Ray Lewis is not the fastest guy or the biggest, but he always plays with focus, intensity and discipline. That's why he makes the tackles other guys can't.
Combine these factors with the lack of training camps for NFL teams this offseason, and we are left with defensive players and teams who are woefully unprepared and unable to keep the opposition from breaking huge gains on any given play.