Having played the game for about a year, I now feel I'm in a position to offer a bit of feedback, and maybe some changes that you could introduce in the future.
1- Too many Touchdowns are scored from kick off returns. I think I scored more in 1 season, than the total amount scored in NFL history. This aspect can make a poor team look good.
2- There are too many long term injuries at lower levels. I averaged 2x 6 day injuries per game, even though my toughness was quite high. This could put people off from staying with the game.
3- Match Bonus should be replaced with 4, and 5 star sport shop equipment. This is a game of Tactical Awareness, so a Match Bonus is only used by teams that are poor, and having spent a lot of time setting up formations, and plays, it pisses me off that a team, that are quite clearly poor, can use a Bonus and get a result.
Overall, the game isn't too bad, but it does have issues that could be rectified by watching actual NFL games, and introducing changes into the game that mirror real life.