I propose to make the competition between the teams more interesting by balancing the workers.
1) Only one worker can be hired at a time
2) The same worker cannot be hired while he is hired (he must first be fired before being hired again!)
3) The level of the team determines how long a worker will be hired. (Maximum team level = 200% time)
Small teams will have cheaper workers with less validity.
Big teams will have more expensive workers with more validity.
What will you offer?