It has been made relatively clear to me that the architects of the game have made it intentionally difficult to get 48 minutes for players in a single game. Managing minutes is not supposed to be easy (one of the charms of the game, I suppose).
That being said (and without looking at the games mentioned here)... here are some tips to make the 48 minute goal a greater possibility (it is never 100%):
1) Dress 9 or fewer players. [If you have 10 players in a blowout game, your player will be substituted out]
2) Make sure each player is put into the rotation. If you dress 9 and only 8 are in the rotation, the 9th guy is going to come into the game in a blowout situation... for someone. Because the AI tends to be cruel, the player will invariably come in for the player you want to play 48 minutes.
3) Place the player you want to play the whole game at all THREE (starter, backup, reserve) positions.
However, doing all of this is not a guarantee of 48 minutes. Playing only 5 players is not a guarantee of 48 minutes either (due to fouls and injuries).