Is there someone here who's good at reading 'mystery cards'?

There are a few more points I thought I should add:

1. Some managers are much quicker at turning over players than I am. In fact, perhaps the strongest manager in a keeper league I'm in certainly fits that description. You'll need to decide which style suits you.

2. There are some players who simply don't have a bad card. In other words, even their worst year is worth their salary. In such cases, don't drop them just because they are underperforming.

3. If you know for sure a player has a good year, don't drop them just because they are underperforming. A huge mistake if you do.

I think Coyote gives some really good advice. I am relatively new to the Mystery format but I definitely fall into the camp of holding on to my players a lot longer than most. I like to be sure, before I drop someone, but to each their own technique.