Your new player Timber Ball had the player ID 60 which belongs to Amy Cobb, a player who played for your team last season. Here is what I believe happened:
When you tried to enter the new player, you hit the b]Edit[/b button instead of b]Create[/b. As Amy is listed first in your team roster, b]Edit[/b took you to modify her player data which you replaced with Timber, and this would be effective for all games Amy ever played.
Use b]Create[/b on the "Add Player to team:" line to add new players. The next window with the data entry fields will be titled "Add new player" rather than "Edit player".
I have restored Amy's name under ID 60 and created a new player Timber Ball for your team, so everything should be ok now. Should Amy not be playing in the league anymore, make sure to b]Remove[/b her from the team so she does not appear in the roster anymore. To later restore her to the team (if she did not migrate to another team), just hit the b]Restore[/b button.