Rui Faria
is a name you probably don't recognize, but you'd be surprised by how familiar his face is once you see it. He was doing a seminar in Barcelona's stadium during the period when Mourinho was assistant to Van Gaal. After that Mourinho saw something in him that made him hire Rui as a fitness coach during his time in União Leiria.
Later on, Mourinho brought him along when he went to manage Porto. There, he was a part of Mourinho's team along with Silvino Louro and André Villas-Boas. Aside from Boas, they all followed Mourinho in his career until he left Manchester United.
Mourinho and Rui Faria got along very well that Faria was doing all things Mourinho was too busy for or say things Mourinho wouldn't say out of fear of punishment. During his long stints with Mourinho, Faria turned from a fitness major to an assistant and opponent analysis. Finally, he was a head coach in Manchester United.
Rui Faria was the one running training sessions most of the time while Mourinho stayed in his office. He was in charge of talking to all different analysts and keeping an eye on the loanees. Andreas Pereira was quoted saying that during his time in Granada, it was Faria who kept contacting him.
To understand his impact you have to listen to Kris Voakes, GOAL's reporter in Manchester United who attended many training sessions. Kris says that Manchester's drop of form during the 2018-2019 season was a direct result of Faria leaving during the summer. In fact, if you check Mourinho's stats, you would see that his third stint was his worst in terms of the time it took him to concede 25 goals during a season.
Do the images in our heads of Mourinho being obsessed with success, paying attention to every detail, someone who criticizes players' haircuts and cars match the reality of someone who doesn't attend most training sessions?
Željko Buvač and Pepijn Lijnders
Buvač was Klopp's assistant for 17 years before leaving in April 2018. Many Liverpool fans and analysts related Liverpool's bad defensive form early in the season after due to his departure. Getting knocked during round 1 of the FA Cup and the Carabao Cup at the hands of Wolves and Chelsea respectively. Also lost three away matches in the UEFA Champions League at the hands of Paris Saint-Germain, Napoli, and even Serbian club FK Crvena Zvezda.
No one knew the full-scale effect of Buvač's exit as Pepijn Lijnders took his spot shortly after. That was the reason Liverpool improved defensively.
In October 2020, Buvač spoke out about how he was "practically the manager for 17 years". His words did seem like a bitter exaggeration as he described Klopp to be a lover of the spotlight. He said that Klopp's team under his leadership was actually doing all the work, and Klopp was just the one speaking for the media. Taking the credit in the process.
I do acknowledge that Buvač's words were mainly a swipe at Klopp. But, when you couple it with Klopp's words describing Željko Buvač as the "brain", and Peter Krawietz, Klopp's other long-serving assistant as the "eyes", while Klopp described himself as being the heart.
Klopp's statement seems to be coming as a humble one. But You just know that the truth lies somewhere in the middle. In Bring the Noise: The Jürgen Klopp Story, Raphael Honigstein talks about the problems that happened during that period as Pepijn Lijnders' influence was rising. Pepijn Lijnders was supposed to be the 4th man at the time.
Željko Buvač saw his role as useless with Pepijn Lijnders getting more space over him, especially with Pepijn Lijnders being more popular among the players. Honigstein also said that Lijnders was getting more into Klopp's ears. How does that affect Buvač? Well, Pepijn Lijnders was the one managing training sessions.
In 2019, Pepijn Lijnders spoke to Liverpool Echo about how he is the one in charge of deciding the team's set-ups ahead of each match, as well as setting up the training to serve whatever purpose needed. He also explained that Klopp was helping him in each step.
Notice how Klopp is the one helping, in a way, Klopp is the assistant in this scenario. In the book, Klopp says that Pepijn Lijnders reminds him of himself. That coincides with how Rui Faria's role at Manchester United and what Ted Knutson said about the roles of assistants.
Pepijn Lijnders' role is so vital that Klopp himself doesn't see himself able of doing what he does. Every time Klopp talked it seemed like he was repeating himself. It is kind of like how your boss says stuff that you don't find relevant anymore. The final result is that Pepijn Lijnders is wildly considered to be the man leading Liverpool when Klopp leaves the club.
In Conclusion
Assistant managers seem to be much more important than we think. When you take into account that someone like Tito Vilanova was
actually the reason Messi switched to the false 9 role, you realize how important they are. Everything we believe that managers do, is actually what the assistants do.