Baseball obviously has it's differences from hockey, but I worked for the Red Sox for a couple years so I tend to cut GMs a lot of slack. The job is way, waaay harder than it looks from a fan's perspective; there are a lot of smart, dedicated people working directly against your interests.
The O'Reilly trade...eh, there's some circumstantial evidence that trade was pushed by ownership, and if your owner says you need to move a guy before his bonus is paid, then other GMs have you over the barrel and you take the best deal you can find.
But...Marco Scandella. Marco f*cking Scandella. Not the most costly mistake, but the move that was most clearly, unequivocally a failure on his part. Botterill traded Scandella to Montreal for a 4th...and 46 days later Montreal flipped him for a 2nd *and* a conditional 4th.
Again, not a terribly costly mistake, but the most clear, unequivocal mistake I've ever seen a GM make, in any sport. This was not a case of a GM misjudging the potential of a prospect - which has happened forever, from Sam Bowie to the first 198 picks in the 2000 NFL draft, to our own Tage Thompson - but a case involving an established player who Botterill *absolutely* should have known the value of and *clearly* didn't.
Every GM makes bad judgement calls. Botterill literally did not know the value of an established player under his control.
Grrr...