games

Goalies are letting in unrealistic goals that I have never seen in real hockey and whatever a player shoots at him is immediately a goal, it doesn't matter what level the game is, that is, whatever he shoots is a goal more or less 

If this were true, every game would have 20+ goals. I'm not saying every goal is perfectly realistic, even though odd goals are nothing new to real world hockey. Regardless, every shot is not a goal.

Players fall near the boards when they touch it or when an opponent touches a player, sometimes one or both of them fall

We'll need video of this. I have never had my player go down for touching the boards. Players colliding with each other can make both fall. This is dependent on different factors. Attributes, player sizes and the force at which they collide mainly. Which is also realistic.

Defenders don't defend as they should and forwards attack less when they don't have the puck 

We would need to see video examples of this. I'm not saying the AI is perfect. There is always room for improvement.