In most cases, the player will perfom badly in your team also.
When i buy, i try to buy players who have some rating available.
If i buy a player that has non, i look at his stats, in the stats menu, after i buy him.
If he has 5s and 6s, i try him out for a game, if he gets 5-6 ain that game i sell him.
In 5 seasons, i have never seen a player who has bad ratings on a team, and good on the next team.