The MLB offseason is a golden opportunity for teams to add missing pieces, plugging the holes that kept them from achieving the ultimate goal the previous year.
Whether it's a splashy free-agent signing, a blockbuster trade or an under-the-radar move that pays major dividends, contenders are built in the winter.
Entering Game 5 of the NLDS on Thursday, five teams remain in the hunt for a World Series title in 2021.
Focusing on those clubs, we'll count down the 10 moves that have had the greatest impact on this year's playoff picture, taking into account how they addressed needs and the impact the players' production has had on their respective rosters.