Battlefield 4 has five-player squads, and it's only so because players requested it. For the longest time, squads in the Battlefield series have been restricted to groups of four.
This change will be one of the biggest the series has seen to its core mechanics.
“They’ve been asking for bigger squads,” producer Aleksander Grondal told Joystiq. “We believe five is a good figure. It allows for more team-based gameplay, basically. You have more options and you can spawn in more places.”
“[Four]was a design choice [in the beginning]– forgive me, I don’t exactly remember why four was chosen. You know, it feels like light years ago from previous games.
“But five is a little better; it gives a bit more flexibility and more interesting choices.”
The extra player will certainly up the versatility of squads in the game, although it remains to be seen how or whether DICE will add an extra, fifth class to fill the extra spot. After all, the reason the previous games featured four-player squads is because there are only four player classes in the game.