So you have the original RED and BLU. The one you see in the comics alot. They are the original team, Hired around the mid 60's. Well, my theory goes that in the other maps / bases that are Mann Co owned, there are other teams of RED and BLU. These teams are later teams hired to cover more ground / territory easily. In this sense, the multiple "classes" you see are small amounts of clones used to fill up the gaps. So, let's say you have 2fort. 2fort can have 24 players or 32 players. If more players are needed, then Mann Co can clone what is of the teams stationed at 2fort. They can also ship mercenaries from other stations for backup, but that takes a while to do. So, that solves the multiple classes idea going on. In the other Bases, BLU, or RED has to control the facility in order to be housed at it. Let's say you have Dustbowl. Dustbowl is housed by Red, but BLU wants to Invade, so, in order for BLU to do so, they must capture all of the points. When this happens, then RED loses the base, and has to flee. At this point, they are no longer accepted by respawn so they have to find a base that is Empty. In the process of finding a base, they have to cross terrain, or use a train to get to the next base. If they die in this process, then they are permanently lost, and cannot be recovered. So, Mann Co has to hire new mercenaries. So, in a sense, every class / mercenary you encounter is a different person, but they are grouped into categories based on their skills. So if one mercenary is skilled in Hacking / Stealth, then that person is going to be put into a spy category. If one is skilled at building / repairing machines / appliances, then they are going to be put in the Engineer category. The original mercs, are the elite set of people that act as a sort of leader for all others. They have respawn access to any facilities. What do you guys think?