Trading down from the first pick in the 2nd round - last 20 years - has only occurred twice.

[Sammy Watkins' Rib]

I looked up the last 20 drafts and was somewhat surprised to see a team has trading down from the first pick of the second round only twice. It happened in 2015 and 2007. 

 

https://www.prosportstransactions.com/football/DraftTrades/Years/2007.htm

 

You would think with nearly 24hrs to take trade calls it would happen more often. Now, the Bills are in a somewhat rare spot where they have traded down twice starting late in the first round to end up at #33. They seem to be a much more willing team to move the #33 pick then perhaps many of the teams that have held the first pick of the 2nd round in previous drafts.