Copied and pasted from the General Hockey Talk:
Unsigned players go to free agency after 2-3 years after being drafted, not exactly sure which it is. I know if you didn't sign Silfverberg, he went to FA.
Players will develop in the CHL and AHL. Players that are eligible for CHL automatically get sent back anytime you try to send them down (to AHL). You will get a notification saying this person must be sent to juniors and will be unable to be called back up for the rest of the season.
Signed non-CHL players have to play on AHL or NHL roster, since there isn't an option to sign them and let them play in Sweden for example.
So if you sign MZ93 you have to play him. If you don't have a spot for him in the AHL, you will have to make one or he will nto play and not get better.
Best way to develop players is to check their potential and focus on the section (Offense, Defence, Athleticism) that is the lowest rating. Then find their lowest rating in that category and set the player training to develop it.
Also I focus on the player type. So if I have a small PLY center and his lowest potential categories are Defence and Athleticism, I focus on Athleticism, since I don't care too much if he won't check.
Don't forget your GM upgrades too. I put most of my points on Asst. Coach so that my players develop quicker.
As far as drafting goes, take players with HIGH league interest. Avoid ones with NONE. The more league interest, the higher potential they usually have. So they may have low ratings, but high potential.
As SD mentioned, be wary of your contract situation. You can only have 50 players under contract. So only sign players (prospects) that you want, and ones that you could potentially lose. So you are safe to leave a player unsigned for 2 seasons. I also like to leave 1-2 contracts free for waiver pick ups (because the computer will waive players because of contract and not potential/overall). So you will see Cory Schneider on waivers sometimes.
To clear up roster spaces, you can trade useless guys taking up valuable roster spaces (like Lessard) away from young guys like Zibanejad. Trade them for 4th-7th round picks. Just keep trying in the off-season to unload them.