It's crystal clear where he excels on the pitch.
But to have so many experiences playing in different positions will help his understanding of the game, knowing what it's like to play in the double pivot at the base of midfield, for example, might improve his runs into space when looking to receive the ball from that position. (I had been playing football for 15i'sh years before the first time I went into midfield, I spent the entire game chasing the ball, I had no awareness of where to stand, how to show for the ball, it was like a playing a different sport, it must have taken me 15-20 games before I felt comfortable and was able to contribute effectively both with & without the ball), but when I went back to my original position I felt a lot more connected to midfield than I had done previously.
It also validates his selections within different formations, tactically he can be useful to a manager who can deploy him without the need to make a sub (Dier was key to Poch for this very reason).
The final thing is that he has only just turned 24! He still qualifies for YPOTY. The lad has played 307 professional games and scored 86 goals!! That's 53 games and 70 goals more than Jack Wilshire has in his entire career!! He's also played 3 more Internationals and scored more than him for England.
x1 League Cup runner up
x1 League Cup Semi-Final
x2 FA Cup Semi-Finals (Scored in both)
x1 CL Runner-Up
Never finished below 4th in PL
World Cup Semi-Finalist (Scored winner in Quarter-Final)
I'll mention it again, he's JUST turned 24!!! Now compare the press he gets to say another 24yr old, who is on DOUBLE the wages I might also add.................
Just 46 apps and 14 goals from Striker!