The tactic didn't really get much attention there, but it looked quite interesting so I wanted to give it a try. As the name implies it's a 4132 Narrow which consists of a flat back four, only one man in either cm or dm and then a narrow front five. My main concern before trying it was that it would get either exploited down the flanks or that the the lone cm wouldn't be able to cover enough ground, but after a rocky first month defensively in my save with Wigan using this tactic, it was surprisingly solid for such an open formation.
With Wigan, a team which was predicted 20th in pre season after my transfers (Esposito was signed for big money in Jan after making some reasonably big sales, but the tactic performed just as well before his arrival), we went on to comfortably secure promotion, amassing a record breaking total of 113 points along the way. The front five positions as a whole spread the goals pretty well between them with 85 goals coming from these position throughout the season (ignore the player stats as I'm also counting goals from players sold in January which adds about 12 onto the total). This offensive success was also achieved with makeshift central midfielders occupying the shadow striker roles while not really being ideally suited to them for most of the season.
I don't feel that a massive description of the tactic is needed as it is effectively surmised in the original FM Scout link (https://www.fmscout.com/a-suffocate-the-opposition-fm20-tactic.html), but my overall description would be that that it's a high pressing and high possession tactic that allows you to dominate games. The most common chances created are when the ball is eventually worked out to one of the wingbacks who then crosses it or cuts it back to a looming shadow striker, so invest well in solid offensive wing backs.
Finding the players to fill all of the roles honestly isn't too hard for this tactic as it's just the kind of players that you'd expect. Quick and offensive minded wingbacks, shadow strikers and advanced forwards that are goal threats but are also well rounded enough to play within a possession heavy style, a creative ap in the mould of an ozil type 10 to unlock defences (Kieran Dowell was player of the season for me in this position on loan from Everton), a dlp which can dictate the play but is also defensively sound enough to hold down the midfield on his own and then just generally good and pacy centre backs (although mine were nothing special in this regard and we were fine defensively).
Other than everything else that has been stated I'd just offer general tips such as working hard on improving the team cohesion which is shown in the dynamics section as I feel it has a very big impact on how the team plays and just have fun with the tactic. It's really good once it gets going and deserves a lot more attention.