Why does great defense beat great offense?

It really sounds creepy as fuck.  

Definition of stud

1.1a :  a group of animals and especially horses kept primarily for breeding

     b :  a place (as a farm) where a stud is kept

2.2:  studhorse; broadly :  a male animal kept for breeding

3.3a :  a young man :  guy; especially :  one who is virile and promiscuous

      b :  a tough person

I'd guess it's because offenses generally need to put together multiple pretty good plays in a drive to score, but defenses only need to put together one great play to end a drive. Even if you stick to pretty good plays (and so don't consider forcing turnovers), the defense ends a drive with three in a row, and an offense needs more than that to score.

A great book called Scorecasting (Sports version of Freakonomics) that goes into different ideas like this and many others that are thought of in the sports world. Worth the read and then pick up the Gladwell books if you like Scorecasting. Link to Amazon

to have offenses that score enough to win. Great offenses still have to have defenses that are adequate enough to hold the other team to a point total lower than their offense.

I'll throw out an idea -- 

Offenses are subject to the Anna Karenina principle. That is, an offensive play has a particular design and for it to be successful, each part of the design has to work. You don't have to stop or interrupt every single part of the design, you only have to stop one part of it.

Now, that's not exactly true -- good play design leaves options on the table. Maybe the QB can audible at the line, or maybe the RB has multiple holes to look for, or maybe the WR's can adjust routes, and they can all do this based on what the defense is showing.

But still, while better offenses compensate for the Anna Karenina principle by giving themselves more possible paths to "success" on a given play, this (typically) has the secondary effect of complicating the play design making it harder for each player (and the offense as a whole) to execute properly. It's a trade-off.

That's my theory. The Anna Karenina principle.

That's what my dad always said.

I don't think it is the case. Look at Boston College this year.

It's a "trusim," but that doesn't mean it's true. Virtually every national champion is strong on both sides of the ball. There are exceptions such as 2010 Auburn (great offense, mediocre defense) and 2002 Ohio State (great defense, mediocre offense), but you generally can't win it all unless both units are among the nation's best.

By FEI, Alabama has the best defense in the country, but Clemson is 6th.  So if Clemson wins, that isn't exactly a victory for offense over defense, because Clemson's defense is pretty great too.

always knows where they are going, and that is a great advantage.  However, most offenses are built off of repetition.  No matter the competition level, the opposing defense is always going to know the basic strategy of what the offense is going to do.  You can look at every team in college football and see what they are trying to do and who they are trying to get it done with.  

To build off that, offenses are always trying to exploit a weakness in the D.   Did you see how OSU went uptempo run-run-run-run right at us? They knew we were weak without Glasgow upfront and tired. 

Defenses win because they can do one thing: not let the opposition easily do what they want to because they have the talent and scheme necessary.  But the key is to not let the "role players" of the offense beat you while doing this.  For example, if it takes the defense 9 guys in the box to stop OSU's running game, are you not going to get burned by the pass? Virtually every offense will be frustrated when their stars aren't getting their customary yards.

Also, it comes down the simple math: the ball on 90% of offensive plays is going to be handled by the QB, the top running option on the field or one of the top 2 or 3 pass catching targets on the field.  So the defense really gets to play 11 on 5 or 6.