teamwork is not a star, its a number. this number cannot be changed
if you are talking about team chemistry, then yes it will go up.
from the FAQ
Players/Staff FAQ
1. What is team chemistry?
Team chemistry is the indicator how well the player is “gelled” with his team. Anything lower than 5 stars (meaning team chemistry 20), and the players performance is impaired. With team chemistry 1 (a newly bought or pulled player has a team chemistry of 1) a player plays about 30% worse. Each game the player plays ads 1 to the team chemistry. Players that are experienced can get 2 team chemistry points each game they play. Each point of team chemistry reduces the negative performance by 1.5%.