I had made the same observation awhile back, but I don't think it's the game engine as much as it is the players.
In the NFL, coaches have to answer to team owners and sometimes fans/media. There is alot of pressure to be competitive. Millions of dollars are paid to make the team as competitive as possible.
In MFN, team owners have to answer to
no one. If a owner is doing something wrong, they typically find this out by trial and error. Sometimes they never figure out how to improve, or sometimes they become inactive. This can lead to games where stats can get bloated.
If a "good team" faces a "bad team" the stats/score can get unrealistic. For example, if a bad team has a hole in their defense, or maybe a predictable offense, the "good team" can take advantage and have unrealistic success. I call this unrealistic because real people will adapt during the game to cover their weaknesses in real time. In MFN you set a gameplan, and see how it goes. There is no way to change your gameplan mid-game to adapt to your opponent. Thus if a team gameplans well against someone who gameplans poorly, the yards per carry or sack total can get pretty crazy by the end of the game.
(Also consider how owners who are inactive or tanking can impact stats.)