Hey dek - hang in there. As with many games, there is a learning curve with 2K, so keep at it.
Most likely it's a few things. Best guess it's a combo of just still learning, plus some thing's you have not done yet or figured out like finding the freelance set that works for you, adjusting your playbook to plays you know well and that fit your team, stuff like that.
What I'd suggest are these changes to get you going -
Adjust the CPU Shooting sliders down to match the Human sliders. The change both the CPU Off and Def consistency to 50 (from the current setting of 65). See how that plays.
Watch your stats and see what else seems off or out of line and we can tweak other stuff if needed.
Far and away my favorite Freelance set is Flow. You will have off ball screens set for players on the perimeter creating movement and open jumpers or possible lanes to drive. I like this set because it triggers so quickly compared to some other sets. Set Flow to the Freelance 1 spot during a game and it will stay there for future games (set once and done).
I find having a Freelance set that you like and learn makes the game so much easier to play.
See if these couple things help.