Workflow is applicable to pages only. You could implement something custom, but this would be completely separate from Kentico workflows.
In order to add players and and teams you could add a separate tab e.g.: Page | Design | Forms | Properties | Custom Tab and place Teams And Players underneath it. Kentico does not recommend association Pages with any custom class, however this is possible. You'll have to use {%nodeid%}
macro in order to retrieve page node id on your custom UI element.
In case you want to show players and teams under the Forms tab - you could implement custom form control, that will list appropriate data.