I suspect coaching has a bit to do with it too. We coach our players to havefood fundamentals, to be able to control and pass the ball, as well as having good decision making skills. All lead to players who are most comfortable in midfield.
The 90's was an interesting time as you say. Branch, Cadamateri, Jeffers, Rooney, Vaughan and Anichebe all within 10 years. Lads like Chadwick and Jevons who also got some game time in that too.
....I’m so old I played lots of representative football with Branch’s Dad, he was a classy defender & was an apprentice with the Reds in the same group as Dave Fairclough.