5. OF Nelson Velazquez
Unfortunately, there was just no room for outfielder Nelson Velazquez on this team. With Ian Happ, Cody Bellinger, Mike Tauchman, and Seiya Suzuki patrolling the outfield and Christopher Morel as the primary designated hitter, Velazquez was effectively blocked. But there are real signs of a solid slugging outfielder in Velazquez, as he's hit 9 home runs and driven in 17 since he's been traded to the Kansas City Royals.
The Cubs received Jose Cuas in return from Velazquez, which has been mostly a fair return. Cuas has been a fairly large part of the Cubs' bullpen, with a 2.81 ERA in 18 games. But I think we will look back on this trade as a mistake on the Cubs' part, specifically when Velazquez hits 30+ home runs in a year.
I think it's unfortunate that Velazquez will no longer be in Chicago, it will be good for his career in the long run. With Kansas City not competing right now, guys like Velazquez will get long looks at the big league level and potentially allow him time to thrive.
Velazquez will forever be responsible for hitting an unbelievable grand slam for the Cubs though. In a contest against the Seattle Mariners in April, the Cubs fell behind by seven runs in the first inning. But the team came storming back in the third inning and put four runs on the board before Velazquez sent a go-ahead grand slam over the wall in left field. It was an incredible moment and a rare thing to achieve a playoff-like atmosphere in an April game.