ESPN recently put together a short little compilation video asking various GMs about the best and worst trades they’ve made over the years. The Brian Cashman segments start at 0:31 (best trade) and 1:57 (worst trade). Here’s the link in case the video embed isn’t working for you.
Cashman has been the GM for a long, long time, but it’s not hard to pick out his best and worst deals. He calls the Alex Rodriguez trade his best — the money aspect of that deal is always forgotten, the Rangers ate so much salary that the Yankees got age 28-31 A-Rod at $16M (!) per year — and it’s interesting to hear him talk about the business impact of the trade, on attendance and cable subscribers, etc. Cashman calls the Mike Lowell trade his worst, which he’s been doing for about eight years now.
Of the top of my head, other candidates for Cashman’s best trade include the Nick Swisher and Bobby Abreu deals. The Jesus Montero–Michael Pineda swap has to be a worst trade candidate until Pineda actually pitches for the big league team. The jury is still very much out on that one, obviously. Tyler Clippard and Ted Lilly are worst deal candidates as well.