It might look like a mess, but there's some method to its madness.
The Sweeper Keeper and Central Defenders on Defend keep things simple and recycle possession to the more creative players ahead of them. The Enganche sits in the middle of the opposition half while the rest of the forwards roam around him with a good mix of finishers (the Poacher and the Raumdeuter) and creators (the Trequartista, the Mezzala, and the Libero) in the final third.
There's also an attempt at left-to-right balance: I found the Trequartista to be less active in their pressing than the Raumdeuter, so the Carrilero sits behind the Treq to compensate for that.
Don't overlook the Carrilero, either. The off the ball movement of the other attacking/midfield roles drags opposition defenders away, which often leaves the Carrilero in quite a lot of space. If you have a player who can capitalise on that either through their passing or their ball-carrying, you're laughing - due to injuries in my test save, I signed Naby Keita in January to play here and he was exceptional.
Pretty standard set of instructions for any possession-oriented tactic: Positive mentality, Play out of Defence, Work the Ball Into the Box, Low Crosses, Shorter Passing, Higher Tempo. The width is left on Fairly Wide because I found the attackers got too bunched if it was set any narrower than that. Focus Play Through the Middle is on because that's where all our players are and we've got a lot of roles that like to roam already in the side, so Be More Expressive has been selected to double down on that behaviour.
Again, nothing too outrageous. We don't have any real defensive structure to talk about, so we can freely counter press without worrying about disrupting that. Having Counter on is a bit superfluous, as this tactic tends to dominate the ball heavily, but there's no harm on having it on. The GK Distribution has been put on Short Kicks because I found that my GK would occasionally pick out the Regista or either of the wide players when they'd dropped off to find space during build-up, which helped the team transition to attack a bit quicker. If your GK has poor Decisions/Vision/Distribution in general, you might want to restrict their passing to just the CBs.
Out of Possession
This is an inherently top-heavy formation, so it makes sense to try and do our defending in the opposition half to stop them getting out - hence the Much Higher lines, the Extremely Urgent Pressing, and the Offside Trap. Prevent Short GK Distribution has been left off, but can be used on a game-by-game basis: if the opposition are leaving their wingers high and wide, you don't really want their GK pinging long balls into them in space. The reason for Forcing Opposition Inside should be fairly self-explanatory.
The only roles with PIs are:
* Mezzala has More Direct Passes and Take More Risks to give them a little bit more penetration on the ball
* Enganche has More Direct Passes and Get Further Forward for similar reasons
* Trequartista has More Direct Passes and Stay Wider to stretch the play a little bit
* Raumdeuter has Shoot More Often to add a bit of cutting edge
* Poacher has Move Into Channels to stimulate a little bit of variation with their runs off the ball
I played through a season on the most recent update with Chelsea to test this out, tweaking the tactic as I went, using Match Prep training sessions, and playing more defensively late in games to hold onto leads. We ended up finishing second, which wasn't terrible considering Timo Werner had a 12 game stretch in the middle where he forgot how to finish despite consistently racking up 0.5xG per game - hence all the draws:
The only time we really got battered using this tactic was away against PSG, Bayern, and Liverpool.
I also simulated a season with Bayer Leverkusen and Sevilla, which both went fairly well:
1) This isn't a plug-and-play tactic
A lot of the roles used here have quite demanding attribute requirements and you're going to see a drop-off in performances if you start sticking square pegs in round holes.
I've also not really gone through and fine-tuned it that much, so there are definitely improvements that could be made if results are paramount for you. For instance, having both the Libero on Attack and the Regista is probably a bit redundant as they sometimes play in each other's space and the Lib(Att) leaves you vulnerable against Advanced Forwards playing up top by themselves. Dropping the Libero's mentality to Support or switching it out for another CB role would make things more solid. Likewise I imagine you'd get better results if you had a more mobile striking role instead of the Poacher (either an AF if you want to be more direct or a CF if you want another roaming role around the box).
2) Exposed Flanks
By virtue of the formation, you're going to be left open in wide areas and you kinda have to make your peace with that. This is a tactic that is going to work better for stronger teams because the opposition are less likely to commit bodies forward against you and, even then, you are going to run into problems against teams who play with two out-and-out Wingers. Your wide CBs are going to have to cover a lot of ground and get through a lot of work, so the more athletic they are, the better (in my test save with Chelsea Kurt Zouma averaged 7.49 in this role, 3rd best avg rating in the league).
I wouldn't necessarily recommend using this against other strong teams, but if you do, you can get your two wide players to specifically mark the opposition's most advanced wide players using the Mark Specific Player PIs and Mark Tightly OIs. I also found that swapping the Mezzala for another Carrilero worked quite well in harder games.
Conceding goals from throw-ins and free-kicks near the half-way line was a bit of a problem as well - in these situations, the team tends to rest in its shape, which obviously causes problems because it leaves opposition wide players unoccupied and I couldn't find a way around that if you're not doing specific player marking.
3) Late Goals
In the holiday tests, I found that the tactic quite often dropped points in games due to goals conceded late on (85 mins+), so I'd recommend pairing this tactic with a more conservative one you can switch to once you feel like you've got a comfortable lead.
As it stands, this isn't a silver bullet, game-breaking tactic, but it is a bit of a novelty that manages to combine some of the more obscure roles in a way that produces some beautiful football at times. Have fun with it!