Players play in lineal mode usually. Only, if you add new players the performance can change.
You talk about old rating, and actual performance. Note that these 2 things are not the same, and then you have to see, the level of the old team, and too, see that the other team have diffeent players and that can affect.
My advice is don't look ratings, test some matches and if contribution is not enough go for others, because sure that there's a better player waiting![]()