In my opinion, does it really matter how tall midfielder,s are.
Its what they do with their feet is the important thing,nippy small guys are normally more beneficial with their low sense of gravity which enables you to turn easier and get tackle's in.
The only problem with to many tall midfielders is that you tend to get to much hg head tennis going on, my only criticism that I had of Garner when he was here.
I don't think our midfield is full of short players anyway,average heights,but not short.
A mixture of height would be ideal,failing that we could give them platform boots.