High quality players have a higher probability to contribute more, especially in matches against high quality teams. However, this is not guaranteed.

If the players are new, I will observe them and probably bench them for a while. If players never perform well for a long period, probably he will never fit tactics of the team. I will sell them even if their quality is high. BTW, I believe some players are less consistent. I will observe their performance pattern, so I keep a record of performance myself.