Well, like any franchise with 40 years of existence, you are going to have moves that you liked (Donaldson), moves you hated (Mike Sirotka), moves that didn't make sense to you but worked out (Lind for Estrada) and moves that make sense and blow up in your face (AA's Jays-Marlins deal).

With that in mind, the worst trade that I can remember occurred December 20, 1996. The 2-time World Series winning manager had a disdain for his LHH 1B who had and OPS+ of 130 over parts of 8 seasons with the club, including flirting with .400 in the second of those World Series years. Cito Gaston felt that John Olerud wasn't the type of hitter he wanted on his ball club, probably because he didn't pull the balls and try to hit HR's. Olerud was a strong contact hitter, who often filled the scoresheet with doubles and walks. Puck & Bat would have said he was Big & Strong, but that didn't matter to Cito.

Dec 20, 1996 - Toronto Trades John Olerud AND cash to the New York Mets for Robert Person

Through parts of 8 seasons with the Jays, Olerud had triple slash marks of .293/.395/.471, hit 213 2B's and contributing 109 HR's. This was good enough for 22.6 bWAR/23.0 fWAR. He also finished 3rd in the MVP voting (behind Frank Thomas & teammate Paul Molitor, though looking at WAR, the winner should have been Ken Griffey or Kevin Appier) in 1993 and was 4th in ROY balloting

Over his subsequent 9 seasons, he continued to pile up doubles and walks on his way to another 35.6 bWAR/34.3 fWAR

The man who he brought back? A young starter with 30 appearances and 101.2 innings to his name at the time. Person was a starter for a year with the Jays, then was put in to the bullpen. Over his 61 games with the Blue Jays, Person put up a solid -1.8 bWAR/0.0 fWAR (this is a guess as he put up 0.6 fWAR the year he was traded, but he became a starter again in Philadelphia and it looks like most of his value was there).

On May 5, 1999 Person was traded for Paul Spoljaric, who went on to throw 62 innings that year and then was traded with Pat Hentgen after the year to St. Louis for Alberto Castillo (released), Matt DeWitt (who was part of the infamous Mike Sirotka deal noted above) & Lance Painter (released). The players who came back in the Sirotka deal were Matt Williams (never played in the Jays system), Kevin Beirne (Left via FA after one year), Brian Simmons (Waived) & Mike Sirotka (never played again)

To recap, after the trade, John Olerud put up ~35 WAR, an All-Star game, 3 Gold Gloves & another 146 HR's.

What returned accumulated a solid -0.8 WAR for the organization.

Robert Person 0.0 WAR (probably a touch high) Paul Spoljaric 0.0 WAR Alberto Castillo -0.3 WAR Matt DeWitt 0.0 WAR Lance Painter 0.4 WAR Kevin Beirne -0.6 WAR Brian Simmons -0.3 WAR

That to me, has to be the worst trade the Blue Jays ever made, and continues to bother me 22 years later.