Let's begin with a mea culpa with an adjoinder. Zone defense works, but only in certain situations and only certain plays. I've criticized zone defense pretty thoroughly that I went out and did the logical thing of creating a zone defense that works.

The reason that I think it works now is because I recently learned that DBs will follow WRs outside of their zone if they are the deepest defender on the play, so go routes aren't automatic zone busters anymore.

Same disclaimer as always. These are my notes on the subject. Use them as you will. Post here if you disagree, so we can start a conversation. Also, of all my guides, this one is probably the most controversial and in flux as I collect more and more data about how to improve this as a game plan.

This guide also draws heavily on ideas that you can find in these threads:

Player weights: https://nfl.myfootballnow.com/community/3/2443?page=7#25168
Basic defensive game planning: https://nfl.myfootballnow.com/community/3/3581
Advanced defensive game planning: https://nfl.myfootballnow.com/community/3/3791

Preface
This entire guide is going to revolve around the 3 Deep Zone and 3 Deep Man defensive plays. In IRL football, the Cover 3 divides the deep secondary into thirds with the RCB, LCB, and Safety taking a third of the field. The other Safety then either goes man up on someone or sits down in the hole while the NCB or LBs cover the curl flats.

We don't really have that in MFN. The RCB and LCB drop deep, but they only play about 25-30% of the field. The safety that drops also plays about 25-30%. So the Cover 3 in MFN only covers about 75-90% of the field. This means you need to pay close attention to where the gap is because there are a lot of offensive plays that could exploit that gap.

So before all you purists out there start, I know this isn't a true Cover 3 Zone. However, just like in the basic thread where I bastardized the Cover 5, I'm going to bastardize the Cover 3 here to have an easy descriptor.


When to Call Cover 3
In MFN, there is one time, and really only one time, to call the Cover 3 - one downs where your opponent is in long to go. And if you want to only call it in one situation, third and long to go. As a reminder, here are the down and distances that constitute Long to go:

1st Long 15+
2nd Long 11+
3rd Long 9+

This feels like football basics 101, but the reason to call the Cover 3 in this situation is because you want to prevent your opponent from getting a first down. The RCB and LCB in the Cover 3 will center their zones 12 yards from the LOS.

By dropping to Cover 3, you are putting your defenders in a position where they can prevent your opponent from getting that first down. Whereas the Cover 5 is going to put all of your players on an island where one broken tackle can lead to a big gain, the Cover 3 allows your defense to swarm offensive players before they can reach the first down marker. This is why it makes the most sense to call Cover 3 on third and long, but you can also use the Cover 3 to your advantage in first or second and long.

The easiest way to restrict calling a Cover 3 defense is to set the Seconday on the Defensive play matrix to only call the 3 Deep Zone or 3 Deep Man (I may also include the 4 Deep Zone or Man or Corner or Safety Blitz depending on what I'm calling).

Expectations
There are some certain expectations to know from the beginning about running the Cover 3. The underneath will be open on most plays. This is usually OK. You are sacrificing the short game to prevent the big play down the field.

If this is so great against big plays, shouldn't I run it all the time? Absolutely not! Zone coverage is still pretty awful against the run. So on downs where your opponent is likely to run or pass, running a single high safety or Cover 2 man is better than running Cover 3 Zone.

IMPORTANT NOTE: Remember that third and medium plays go from 4-9 yards to go. This means running a Cover 3 here is not advised because of where the CBs center their zones. On third and medium, they are actually too deep to prevent the offensive player from reaching the first down marker.

Benefits of the Cover 3
OK, so what are the benefits about having a specific coverage assignment that you're only going to call a few times a game? There are two big benefits: it puts defenders in passing lanes and it opens up the zone blitz.

Passing Lanes
The biggest benefit of the Cover 3 against the pass is that it puts players in the passing lanes. There are a number of unrecorded knockdowns that happen in the game by defenders that are between the receiver and the QB. Cover 3 plays that have the LBs drop into zones put a lot of players into the passing lanes.

Zone Blitzing
There are a number of Blitz 1, 2, and 2+ plays in the 3 Deep Zone and 3 Deep Man plays. The great thing about the Cover 3 is that you can call these zone blitzes without too much worry because of how your defenders are dropping deep. The problem with man-to-man blitzes is that it means that players man-to-man have no help. Zone defenders tend to flow to the ball much better and prevent those big plays from happening behind them.

There are also some really good CB and Safety blitzes that run a Cover 3 behind them. If you are going to use these plays, you need to be careful how you call your LBs or you end up calling all of your other CB or Safety blitzes on Long distance downs when you might not want to.

Play Selection
Putting players in passing lanes requires that you have some understanding of how zone defenders need to be spaced. As mentioned earlier, the CB zones are centered 12 yards deep and the Safety zone is 15-18 yards deep in most of the Cover 3 plays.

IMPORTANT NOTE: You only want the 3 Deep plays where both of the CBs play deep. There are a few 3 Deep plays where the CB plays a short zone. DO NOT USE THESE PLAYS. The short zone plays are complete ****. The CB ends up watching a receiver run right by him most of the time.

Linebacker and nickle back spacing is really important in the Cover 3. Since your CBs will be playing the deep left and deep right, your NB and LBs need to cover the hole - the space between the hashes from the LOS to 10 yards deep.

Fortunately, you can do a pretty good job of evaluating NB and LB spacing when selecting defensive plays by clicking on the play and switching to the Diagram tab. The most vulnerable part of the hole is the left hash to the center of the field. Many of the effective 113 short and medium passes send the slot receiver on a slant into this part of the hole. The 014 Slot Crosses sends the slot into this part of the hole. And the 212 Slot Crosses, twins Slants, and twins Strong Flood sends either the WR1 or WR2 into this part of the hole as well. You need to make sure that this part of the hole is covered for this reason.

For the rest of the spacing, you need to make sure that your LBs are not bunched between the the hashes (there are a few plays where this happens) and they actually cover the entire field.

Players Weights and Personnel Overrides
Running a Cover 3 successfully requires having two sets of player weights and making use of personnel overrides.

Your best Zone CBs will not always be your best M2M CBs, so you'll need a second set of weights to evaluate when you need to sub in a zone CB. I treat these weights similarly to how I treat my other CB weights except that I drop M2M and B&R Cover to 1 and set Zone cover to 70. I then use the sticky note function to write down who my best zone CBs are.