A 4-2-5 and a 4-4 scheme (Virginia Tech) are not terribly different in general. You will need quick SS types to play LB in a 4-4, or matchup on TEs and the like in a 5 DB secondary. What is different about what Patterson does is in how he teaches it. When I read these articles, I was surprised at what they do in installation. Most coordinators will tell you that your coverage works with your front 7's alignment, i.e., one can dictate the other. You dont do crazy things with your LBs in a normal 4-3 because they could be totally out of position to get into their zones or man-coverage on a pass play.
But Patterson teaches them totally separately and believes the coverage is totally independent of the front aligntment.
Our fronts and coverages have nothing to do with each other. The front is called by the use of a wristband. We break down our first 6 or 7 opponents and put the fronts on the player's wristbands. We dont have to teach anything new to our players during the season. The team's may change, but the fronts do not. We do teach during the season, but we dont have to re-teach our fronts.
Patterson's then does one other thing other coordinators dont: he divides his secondary coverages into two calls called by the safeties to each side. In effect, his FS calls the coverage for one side, and the Weak Safety for the opposite side, dividing the offense down the middle. Most teams check off their coverage and make calls based on formations, but Patterson does not do this. In his words:
“We divide our packages into attack groups. The 4 DL & 2 LB’s are one segment of our defense. We align the front 6 and they go one direction. The coverage behind them is what we call a double-quarterback system. We play with 3 safeties on the field. We have a strong, weak and free safety. The free and weak safeties are going to control both halves of the field. They are the quarterbacks and they will make all the calls…
…In our coverage scheme we are going to divide the formation at the center every snap. We play with 5 defensive backs in the secondary…
…[If the passing strength is to the defensive left] the FS calls ‘read’ left. The FS is going to talk to the LCB, SS, and the read side LB. The weak safety aligns on the other side and talks to the right corner and right LB…
…Starting in spring practice, the 1st Mon. we teach Cover 2 (Robber). On Tues. we teach our Blue coverage (quarters)….On Wed. we teach squats-&-halves coverage (Cover 5). After that we are done teaching our zone coverages…
…We don’t worry about formations any more. When you divide the formation down the middle, to each side there are only 3 formations the offense can give the secondary. The offense can give you a pro set, which is a tight end and wideout; a twin set, which is 2 wideouts; or some kind of trips set that the defense will have to defend. That is all they can give you.
In 3 days we teach our kids to line up in all 3 coverages against those formations…when we start talking about our game play, we never talk about lining up. All we talk about is what the opponent is going to be doing and how we are going to adjust to it.
Unless the offense lines up in a 3-back wishbone or a no-back set, there are only 3 ways the offense can be aligned and still be sound. Unless we want the coverage to overplay something to one side, we don’t worry about formations….
The Defensive Front
Basically, they normally align their DT’s in a 3-tech to the strong side, and either a Shade or 1-tech weakside. This is similar to what Clemson put against Georgia Tech. The advantage of playing your Nose Guard shaded off the Center's shoulder is that when he charges inwards, he can control both A-gaps. Their DE’s align in a 6-tech (head-up on TE) if there is a TE and in a loose 5-tech if no TE (just outside the OTs shoulder). Essentially their front will align either to the boundary/field (short/wide side) or a slight change based on whether a TE is on the OL. They do not flip-flop their DE's based on the formation or hash, only their DTs.
In blitzing, a small number of relatively simple calls can be combined into 157 distinct calls. But with the way he has simplified it, a DT only has to memorize 6 words to accomplish a variety of maneuvers and stunts.
…(When we blitz) the secondary doesn’t care what is going on with the front and LB’s. All they know is there is going to be a blitz and both LB’s are going to rush. That tells them they have to cover everybody if there is a pass…
…If there is a double smoke (an outside S blitz from both) being run, the FS knows the SS and WS are blitzing off the edge. He has to talk to the 2 LB’s to get them into coverage…
As far as blitzes go, its not the usual zone blitz with Cover 3 behind it that most teams, including Clemson, tend to run because of the split coverage to each side. TCU is not a heavy zone-blitzing team. They will blitz with Cover 2 Robber behind it, but for the most part are playing straight Man with a blitz. An offense cannot run base man protection schemes against them, because of their use of the twist and slide games (stunts essentially).
For the majority of the time, TCU is a Cover 2, Cover 5, or Man defense, but with Cover 3 in zone-blitz situations. What they tend to do against 2-back sets is slide a safety down into the box, so it looks like a 4-3, and play Cover 2 Robber to the side of the passing strength.
…In the secondary we have 3 basic zone coverages. We split the difference in those 3 coverages and it gives us 9 total coverages…We can also play cover 25. That means we are playing Cover 2 (Robber) to the FS side and Cover 5 to the weak safety side. The 1st digit in the number is the FS side and the 2nd digit is the weak side…
The problem with a 4-2-5 has usually been inadequacy against the rush. Against a Strong offset-I formation, for example, TCU will shift their LBs over to the strongside (called a slide) and slide the WS down into the box at the last second. With 3 DBs playing on the strongside, the Robber coverage call is unaffected. Despite the lack of another LB, TCU still manages to have one of the best rush defenses in the country because of these presnap shifts.
What is Cover 2 Robber? To the 2 WR side, for example, the SS and CB will matchup across the LOS with the FS playing deep-half. The FS watches the backfield for play-action, and once he reads pass his eyes immediately go to the #2 (slotman). If #2 runs vertical, SS stays with him. If #2 runs an out, the SS waits for #1 and is watching for a curl or post route by watching the guy's hips. He'll be underneath the route most likely to "rob" it.
If the hips sink, he's going to break and stop (like a curl). Then the SS jumps the route. Otherwise he goes with him on the post.
If #1 runs an in/out route, the CB calls "in" or "out" and the SS must get under the route to "rob" them. The CB is not responsible for them. On posts, the FS is meant to get under
On the weak side, there will only be the WS and CB on the #1 receiver, and the combination will play what is called "squat and half" coverage or "bracket" coverage. This means the CB will come up to try to squat or sit on routes (bumping the WR at the LOS) with the WS playing deep coverage. Bracket coverage looks a little like a Cover-2 zone, except that the first defender never peels off the receiver to defend the flat. Both defenders maintain high-low coverage throughout the receiver's route. Note that by "weak" I am talking about passing strength, not the Split-end side. The weak side would be a TE and Flanker, which are not as good at receiving as two true WRs to the strong side.
Cover Blue: Cover Blue is a cover 2 "Read", where the FS and WS both have halves, and the corners are in a read (called Blue technique) which means they will follow the #1 receiver vertical unless #2 releases outside before 8 yards deep. In this case the FS and WS will cover the #1 receiver. In a sense this is also Cover 4 (quarters).
Together with a cover 2 robber scheme to the other side, recall the coverage is called by the S to each side, it would be difficult for the QB to read.
The difference between robber and blue is who has flat, curl and wheel responsibilities. Cover 2 Robber: CB has #1 deep and post. SS has #2 flat, curl. Generally on a wheel route, they run the FS down and leave the SS underneath. FS has #2 vertical. If #2 runs an out, rob #1. Blue is 2 read but safety run support (SKY). CB plays outside #1 but on top of route if #2 blocks. If #2 to flat, CB stops feet and WS gets over top of #1.
Cover 5: A true Cover 2 look with CBs in Cloud (they have run support). The Free and Weak safeties are playing 2 deep zone with 5 men playing zone underneath. In other playbooks I've read, Cover 5 is a Cover 2 Man-under scheme, but not in TCU's. Also, TCU runs a matchup zone coverage like Clemson does now (not like V. Koenning, who ran a spot drop, like BC does) so it might as well be man/man. They almost never play the whole field in Cover 5, only one side.
Highlights of them shutting down Texas Tech: