It's common knowledge that when you get to third and six or greater, more often than not, everybody viewing the game knows that, you are are going to pass. Even if you call a running a play and fool the defense, unless you've got an overpowering offensive line and have full backs and wide receivers who have superior blocking skills, first down will not be accomplished. NFL and most college defenses are too fast for trick plays and will be snuffed out promptly.
Think your team has speed? In most cases there isn't a huge difference, especially at the college and pro levels with the speed of wide receivers, defensive backs and corners. Most of them will be able to run 100 meters (to give you an idea that is just under 110 yards, more than the length of an entire football field) in somewhere between 4 and 4.5 seconds.
So how does one decide how many yards a team has to go before it's officially third and long? Sportingcharts.com defines third and long as needing six yards to go or more for an offense to achieve first down.
This means that when an offense orchestrates a passing play and wants it wide receivers to run say 12 yards upfield and then an additional 4-5 yards to the side or middle of the field that is at least 2-3 seconds the offensive line has to keep the defensive line out of the backfield to prevent it's quarterback from being sacked, something which could be considered a gargantuan task with some defensive lines. The timing also does not take into account for when defenders try to jam receivers at the line which can cause them to take more time to get downfield.
A graph on AdvancedNFLStats.com shows that the probability of a first down on third and six or more is less than 1 percent. So the next question would be how does a team prevent getting into third and long in the first place? There are two simple things you can do: 1. Establish a running game at the very beginning; 2. make most of your passes relatively short with receivers who can run precise routes. 3. Have a strong offensive line. Why do we want to accomplish these two things? Here's the breakdown:
With the running game
If you have a strong running team this means the defense has to respect the fact that you could run or pass on any play. If executed properly, establishing the running game could potentially put the offense on it's heels, especially if you have any combination of a running quarterback, a full back who can run or two running backs.
So why could having a strong running game put a defense back on it's heels? The reason is because this means the defensive line has to wait to see if the ball is going to be handed off by the quarterback to either the running or full back before it can just rush the quarterback. If you just rush the quarterback, when he is handing it off to it's other backs then it will be a long day for your defense.
With the short passing game:
With a short passing game versus a long passing game the offensive line doesn't have to hold as long, the passes are much simpler and if receivers run their routes correctly, more often than not they will be open for their quarterback to throw to. The other factor is since the wide receiver is closer to their quarterback the ball won't take as long to get there, therefore the defense won't have as much time to adjust.
Have a strong offensive line
The primary purpose of the offensive line is to protect the ball carriers from the defenders so they can gain more yardage. Offensive lineman do this for running backs by creating holes for them to run through. They do this for quarterbacks by preventing defensive players from getting into the backfield.
Of all the positions on the football field, offensive lineman are the hardest to measure because they are merely a quantifying factor into both the running and passing games. However, according to NFLstats there are two sets of metrics which offensive lineman are measured by. The same metric also applies for defensive lineman.
One is called WPA and the other is EPA, both of which are simply the percentage of positive plays versus the number of negative plays that an offense may execute or not. The only possible issue with these set of stats is it is hard if not impossible to judge each individual player by whether a play was considered successful for a player or not.
Here is an example why: If defender A gets into the backfield and sacks the quarterback and defender b is knocked down by the offensive lineman then there is no reason why defender b should get credit since he didn't do anything to contribute to the play.
So what is necessary to prevent third and long? Have a strong defensive line, establish the running game and have your wide receivers run strong passing routes.