Man, you guys are so negative. We're almost 1st, almost playing beautiful football, and on course to win the Scudetto this season and the UCL next year. What else do you want?!!
The problems of such best XI made by rating websites like sofascore are that first, these lineups are generated based on the ratings, which could be very controversial. Second, too often players are shoehorned into positions where they don't actually play in that year/season mainly because there are no subcategories of those positions.
I think its just natural decline with age, nothing unusual. Hes still solid for the most part but they should start planning for his departure sooner than later, or at least a transition to a smaller role. Huijsen can start getting integrated next season.