The Running Back (RB) and Full Back (FB) are are the two backs in the O'Brien who have an opportunity to run the ball past the line of scrimmage (LOS). While the RB is the focal back in the formation the FB will need to be able to reverse the field through counters and reverses.
I will not spend much time on the type of athlete for the RB. The faster the better! He does not need to be a good blocker or pass catcher as he will not be called on to catch the ball and has very easy blocking assignments on passing plays. If your QB is not able to throw the ball then either the FB or the RB can be tossed the ball to make the throws. Ideally, it is best for the QB to make the throws as the blocking angles become harder when the other backs have to pass.
The type of athlete you have at FB will determine the expansiveness of the playbook. The ideal FB is fast and a great blocker. He will need to have good hands as he is often asked to catch shuttle passes. When you have a better offensive line, his ability to block can come second to his speed. However, if your line is not able to block an athletic defensive end then he will need to be able to assist and or block the DE himself. A slower FB will result in an inability to run reverses and will limit the success of counters. We have often had slower FBs and we utilize the inside receiver and QB more when blocking the counter plays.
The RB lines up two yards behind the QB and about two yards from the inside foot of the center. The FB lines up between the inside and outside receivers even or a half yard in front of the QB. (Figure 1) The FB can also line up outside the outside receiver and we call this the "Hammer" formation. (Figure 2) The reason you would hammer the FB is to get him closer to the LOS so he can assist with blocking the DE. This formation also allows for you to shuttle him the ball on a reverse.
We instruct the RB to always move laterally when taking his first two steps. This is crucial to insure the correct pitch depth between the RB and the QB after the snap. This is a natural path when running the sweep outside the end. However, when running the ball between the IR and OR, the RB often makes his first step toward the hole. Do not allow this bad habit. You must instruct the RB to take his first steps laterally and not up the field toward the LOS.
Coaching Tip: We set up cones when teaching the RB how to run so as to insure he moves laterally when catching the pitch. He is not allowed to knock over a cone.
The RB is also instructed to follow the QB. Where the QB goes he should follow.. even when the QB goes the wrong way! I can not stress enough how important this is to the success of your run game. You want the RB to have his hand on the back of the QB when they reach the LOS and to cut off his block. I could retire if I had a dollar for every time I had to tell the RB that the QB is not allowed to score because he is not carrying the football. It should not be possible for the QB to be untouched and us not score unless the RB is to far behind the QB or decided not to follow his block.
The FB must make sure he does not telegraph where the play is going. If he is angled toward one hole or another it will be a tell to the defense of the direction of the play or that a counter is being run. He needs to line up parallel to the LOS with his hands on his knees. The FB is primarily asked to block either the DE (Sweep) or the LB which lines up (or appears) bock between the two receivers on the "Dive" play. He is also used in counter plays 3. On the counter, he will take a hand-off from the QB and cut inside the right shoulder of the center. On the shuttle, he will line up in the Hammer position and take a shuttle pass, again cutting inside the center. He can be called on to reverse the field where he takes a hand-off on the outside of the QB; however, this play tends to only work at the JH level as most varsity DE will protect against the reverse.
The next segment will discuss the lineman and their responsibilities