Baseball is a thankless sport if you're a general manager.
Between free agents, trades and drafts, baseball GMs have a profound impact on the future of their respective franchises. They can find the diamond in the rough who becomes a cornerstone player during a World Series run, or they can grossly overpay for a veteran who's over the hill and leave their club financially strapped.
No GM or owner is perfect, but the ones responsible for the moves on this list may need more than a sleeping pill to be able to sleep at night.
Here is every MLB team's biggest regret ever.
Dmitriy Ioselevich is a Featured Columnist for Bleacher Report. Follow him on Twitter for all your MLB news and updates.