When you watch Saturday's Ohio State-Michigan game, you will notice the Buckeyes' offense in various unbalanced line formations. This week's class will break down the unbalanced line and some of its variations.

What is a balanced line?
In a normal or balanced formation the line has a three-man blocking front consisting of a guard, tackle and tight end to one side of the center. Normally, an offensive will employ one or two tight ends to create a three-man surface adjacent to the center on the line of scrimmage. Below, you will find examples of a normal balanced formation using one and two tight ends.

What is an unbalanced line?
In an unbalanced formation, the offense will create a stronger blocking surface to one side of the center by either aligning a tackle, bringing him over from his normal position to put him at tight end or actually creating a numbers advantage to one side of the center. One of the most common forms of an unbalanced line is to put a tackle at tight end to the three-man side and the tight end to the two-man side. Below is an example of this concept. Notice the "Z" is aligned to the tight-end side and off the line of scrimmage to make him an eligible receiver. The "X" is on the line of scrimmage to the tackle side making the tackle ineligible.

Why unbalanced line?
There are several reasons why an offense will utilize unbalanced formations. First, the unbalanced line can cause confusion for the defense. Many defenses align their personnel based on where the tight end is aligned in the set. Putting a tackle over creates confusion for defenses on initial alignment. Secondly, it can cause personnel mismatches. By putting a tackle at tight end or creating a four-man surface, the offense causes mismatches with big offensive tackles aligned on smaller linebackers. This can be a big advantage in the running game. Thirdly, the unbalanced line forces defenses to adjust. Obviously, there are many types of unbalanced formations and every one causes the defense to deviate from their normal adjustment and plan. This forces the defense to spend valuable practice time adjusting to formations that the offense may or may not use.

Different unbalanced formations and why they are used
1. Tackle over
The tackle formation (diagram 3) is used to get a big offensive lineman on a smaller linebacker to the three-man side to help in the running game. The advantage is the offense still has the tight end, "Z" and "X" as eligible receivers. This can confuse the defense in alignment and also in man-to-man coverage.

2. Tackle over - Unbalanced twins
In this formation, once again the tackle is over, but also notice both receivers are over to the same side to create an unbalanced twins formation. This creates a three-man blocking surface, but also gives the offense the advantage of having two receivers on the same side. Many times the offense will sprint to the twins, using the big tackle as the extra pass blocker. The tight end is still eligible on the back side.

3. Unbalanced - Four to one side
In this set, the offense will bring in an extra tight end. This formation moves the left offensive tackle over to the right side and utilizes the extra tight end as the fourth blocker to one side. This causes the defense to do one of two things: shift their entire front over or adjust with the secondary. If the defense adjusts with the secondary, the offense has an advantage with a big tight end blocking a smaller defensive back at the line of scrimmage.

4. Unbalanced - Five to one side
The offense may employ three tight ends in the game at one time to create a five-man blocking surface to one side. This causes the defense to shift over to align in a sound front. The offense may run plays back to the short side if the defense over commits to the five-man surface.

Conclusion
There are obviously unlimited ways to create unbalanced combinations. They not only cause confusion for the defense, but they can also cause personnel mismatches. Ohio State probably uses the unbalanced formations more than anyone in college football to help them with the running game.

Q & A with Bob Davie
Thanks for all of the terrific responses and knowledgeable questions this week. Please keep sending in the questions and we'll tackle as many issues as we can this season. Here are a few of this week's questions:

Do you thing the mobile quarterback is what you need now in college football?
Joe Smeins
Iowa City, Iowa

Bob Davie: In my opinion, you have to have a quarterback who can run. Iowa is a prime example. Think back to how many bad plays Brad Banks has gotten the Hawkeyes out of this season with his escapability. There is no doubt in my mind that to be balanced on offense you have to have a quarterback who can beat you with his legs as well as his arm.

In the victory scheme, why not line up your four fastest backup DB's two or three yards outside of both tackles and have them rush to the QB's drop point to present him from getting outside to set his feet and crank up a bomb like Kordell Stewart in the Colorado-Michigan game in 1994?
Mark Duncan
Dallas, Texas

Bob Davie: I think you bring up a great point. Many times what defenses will do as part of the substitution package is put their fastest rushers on the field. You can't let the quarterback break contain and buy more time so the receivers can get deeper down the field. Containing the quarterback and keeping him in the pocket is the most critical thing.

I understand why you want the different substitution packages, my question, however, is how do you know when to sub in and out? Do you watch the other team's sideline to see that they are taking out the TE and putting in another WR? Does someone upstairs look to see who is running in and out of the huddle?
Jeff
El Campo, Texas

Bob Davie: There are two schools of thought. First, you can matchup when the offense changes personnel. This is the ideal way of doing it, but sometimes there can be confusion because offenses hide their personnel groups and you may not know exactly who is on the field. Ideally, you would like to substitute your defenders when they put extra receivers in. The other way is to substitute by down and distance. When it's second or third and long, you commit to your nickel or dime defense regardless of the offense's personnel.

Send in your Football 101 questions. Bob Davie will answer a few of them next week.

Editor's note: As architect of top defenses at Texas A&M and Notre Dame, Bob Davie is recognized as a top X's and O's coach. This season, Coach Davie analyzes offensive and defensive schemes as part of his season-long course on football for ESPN.com. Each week, he breaks out the chalkboard and break down the X's and O's in college football.