I actually reckon that's the best way of judging the best.Still deserves to be up there. I guess if we were to phrase the OP as 'what would trade for this midfielder' everyone would be offering whatever what they have. He's an exceptional midfielder that's had a down year.
You factor in their body of work, and what they are likely to produce if they are on your list for the next 2 to 3 years.
Based on that, I have a top 8, with a gap to the next tier:
1. The Bont
Oliver, J. Kelly, T. Kelly, Coniglio, Shuey, Pendlebury, Mitchell