I have created a bunch of leagues and seasons for Power Play Hockey. I deleted individual defense ratings since the goalkeepers average displays the real actual team defense (IMO). If you want defense ratings, the game instructions will tell you how to do them and go for it!
I have devised a new rating, INJ. To avoid overuse of high rated players with very few games played, this is the best system I can think of, as well as an alternative way to play players that played for two or three teams in a season in a realistic fashion. Before your contest, roll two d10 and read them as a percentage. If the player's rating is within the dice range, he will sit out. Example if INJ rating is 50 and you roll a 49, the player sits out. If you run short of players, you can re-roll or insert the players needed that are the lowest rated. Any questions feel free to contact me by email.