What is Form Score and how does one maintain it?

They need to have a popup or something explaining the form score more, but it seems you need to score goals in every single game and not let any goals go against you to get a good form score, it's very ridiculous to have to score a goal a game to get a good form score. I'm playing my pro on all-star difficulty and moved up to the 1st line about 26 games into the season. To get to the 3rd line in the NHL you need to get the 80-form score in the preseason. Once you get to the NHL season there are a series of challenges with ever higher form score challenges, had to get I think an 80-form score to get to the 2nd line and a 85 form score to get on the 1st line on the 1st line you need to maintain a 90-form score and a shooting % of 13% to maintain the 1st line. It's very unrealistic since most of the 1st, 2nd and 3rd line players on my team are mostly in the minuses, and most are below 5 goals. It would be nice if those challenges would affect other teammates.

I agree. Irl, even the best players in the world get shut down sometimes. And based on EA’s criteria, very good players would all be relegated to the fourth line. It’s not a matter of getting good. It’s extremely unrealistic and downright frustrating. 

it's just so lazy. after over 5 years of doing nothing this is what they come up with? and keep in mind form score is far from the only problem with this game mode it is just the problem that finally makes the game mode unplayable

Form score is strictly based on point production, mostly goals. If you get a goal, you are pretty much guaranteed a form score greater than 80, unless you give up a bunch of goals.

otherwise, the simple answer is this was a task probably relegated to an intern over at EA sports and then was not QA tested by any user (unless they played on rookie). 
I recommend you stop playing the game until they fix this.