I think a good possibiltiy for a sleeper candidate at this position is the Cowboys' 2nd round pick Anthony Fasano. With Dallas lining up 2 TE's in their base offense this year and the proven ability of Bledsoe to spread the ball around, Fasano could emerge as a steal in the later rounds.
It's a mistake to look at Fasano as strictly a blocking TE as Parcells sees Witten and Fasano as interchangeable.
