They traded away 4 time all-star (3-time before the trade) Starlin Castro because they had "too many" players.
I know the Cubs won the world series with Russell on the roster but I think the outcome stays the same with Castro on the roster.
Castro is a .280 career hitter and is on pace for at least 3,000 hits. Russell's best season was .250 but he "takes more pitches and walks." 15 more walks for Russell, 25 less strike outs for Castro.
While Russell is a good fielder, he isn't much superior to Castro. Better? Sure. Castro averages 2 more errors per season. .973 for Russell .963 for Castro.
Russell still has a lot of talent as he is still a pro and I will give him credit for that.