Christian Eriksen. There's a discourse that suggests he isn't performing.
Eriksen is perceived as our central hub for creativity and vision. The perception is that he should be far more dominant during games. That he should control more rather than be reactionary. He starts out on the left to accommodate others centrally, but his role isn't to remain on the flank. He attacks space and looks for opportunities to thread balls. He isn't naturally defensive but then a player that seeks to get forward has to focus more on the potential for space ahead of him than what's happening on the back-foot.
Because of the way we shape up, it's the system that takes precedence over completely free to roam individualism. It means everyone has to work to keep the team tight which places constraints on players but also allows for expression. The system creates the freedom without surrendering it. That doesn't mean we're shackled creatively. It simply means the players are in sync to how the rest of the team transitions and supports.
Perhaps Eriksen is better suited to a more central role to be more consistent, but then is he bulky enough to cope with the pressures he'll face in a fixed position? Having him float around in the final third relies heavily on how we look to pull teams apart (positionally) and if he can find that all important space to accept a pass and push it into the path of a team mate. If we don't play well, he probably won't find a way to change the games momentum. That's not to say that Eriksen is devoid of finding equilibrium in games (along with match winning moments by being in the right place at the right time or deadly from a set piece).
Often he's just done that and found balance with everything going through him. You can hit a rhythm as a player and boss it, always in the right position, always puncturing the defensive wall. Unless you're a Gareth Bale at Tottenham type of player with dynamism at full pelt or you're box to box and can attack 'down the spine' then you have to go down the route of more subtle and delicate movement. Alli and Demeble are free to marauder down the middle. Eriksen has to be less obvious with his outlet. It's a less deliberate environment to work in.
It's an interesting conundrum for sure if you believe there's an actual problem to solve. He has the ability to unlock defences and with football being so organised and regimental these days, getting that chance to assist or assist the assist (the Luka Modric special) might only crop up a handful of times during some games. It's easy to be commanding and controlling when the opposing side allow it by inviting us to attack space. Not so easy when said space is suffocated.
Whether a different type of player is better suited in the system is altogether another debate. We don't play with traditional wingers. We need players with grey matter and instinct to cut in and send balls back wide for the overlap or across the box / diagonal into the box. Eriksen can do all this. Maybe the issue here is that our expectations of him match up to more traditional responsibility that doesn't actually fit into the football Pochettino has instilled.
Whilst I sit here and scratch the chin, theorising about players and positions, it's probably worth mentioning Eriksen is only 23 years of age and Pochettino's system is still fledgling.