I agree with you that being assistant manager to EV would likely be better for him than coaching Barca B.
Xavi is a football nerd through and through. He's more perceptive and observant than any player I've ever seen and this really came to light in a lot of his interviews after leaving Barca. I'll link them here. I know a good chunk of people on this forum will have already seen at least a few of them but I think those interviews are gold and everyone should read them as thoroughly as they can:
http://www.sofoot.com/xavi-clearing-the-ball-is-an-intellectual-defeat-453815.html
https://www.reddit.com/r/soccer/comments/7p00f4/xavi_interview_with_el_país_january_8th_2018/
https://www.fourfourtwo.com/features/big-interview-xavi-inside-mind-a-football-genius?page=0,1
http://www.marca.com/en/football/barcelona/2017/09/01/59a9581c22601d0b658b45b7.html
It's fascinating to see the kinds of views and football wisdom he developed over his near unparalleled career. Tactically, his knowledge and vision is already where it needs to be. It already seems like he has a good idea of what kind of coach he's going to be and the kind of football he'll play. He shows in these interviews that he has a keen mind for analyzing situations and seeking out clear solutions, asking critical questions. It's not just an instinctive football genius but an overt, conscious one that he uses to understand everything that happens or should happen on a football pitch. He says it himself, football is played with the mind.
Everything he's talked about is what you want to hear out of a potential Barca coach. He clearly has the same football-OCD that Pep has and fully commits to Cruyff's philosophy. It's also impressive how he recalls the different training methods of Rijkaard, Pep, Lucho, etc. and exactly why they did it. He even goes in depth about how guys like Dembele could better adapt to the Barca system. And it's not just Dembele or Barca players, he analyzes and compares players from several different teams and footballing backgrounds to make his point about how the game should be played and what makes a "star player".
Xavi is already ready to manage, he's probably smarter and more knowledgeable than half the top coaches out there right now. Going to Barca B to fiddle with tactics and build a system for inferior/developing players is little more than a waste of time for him. An unwritten, obligatory step that we somehow decided every homegrown Barca coach needs to follow to be "ready" for the first team. What Xavi truly needs now is to learn how to lead. How to control a dressing room and motivate his team, how to instill a winning culture within a group and develop the younger guys or fringe squad players. And there's no better place for him to learn this than our first team.
As an assistant manager he'd have a big role in communicating with the players and handling the dressing room. After all, the assistant manager often acts as the conduit between the team and the head coach, so he'd be getting a lot of hands on experience dealing with the players directly. Our core will have been recycled heavily after this summer, with new key players like Griez/Coutinho and other developing players like Dembele/Aleña/Arthur ready to be central to our title races. The squad will be more fresh and hungry than it has been since 2015. Imagine Xavi there to mentor and teach the younger guns in the squad what it takes to be a true champion and what they're missing in their game. Imagine him there to help knock some sense into Valverde about where we've been going wrong tactically and offensively. It changes the dynamic of the team quite a bit, to have an idol there who's ready to teach you everything he knows and watch over your shoulder.
I think Zidane's presence as Ancelotti's assistant coach was huge for RM. Xavi would help with team morale, mental strength, cohesiveness of the group, etc. These are all 'intangibles' when it comes to chasing titles but they are crucial for any championship team and one needs to look no further than RM's mental edge over every single CL opponent they face to see why. It's not enough for a team to be playing great football with lots of talent, a team needs to be READY to be champions and have near unshakeable confidence to do it.
He's ready now. Not 3-4 years from now but right this summer or next. He doesn't need to get his coaching badges to be an assistant manager and he can work on that as he goes until we're ready to move on from Valverde.
