How can I improve my fantasy basketball team?

The only way to improve your team is to know exactly which players are going to perform best in the future. Therefore, the results of any move are uncertain. There's no need to overkill a particular stat, so you're right, you can sacrifice ppg in favor of another stat where you're relatively weak... But without your league scoring system and the stats of the other teams in your league, it's impossible to say who you should trade for...but team I looks good to me