The translation manager should be able to set or modify the permissions for specific languages (Source and Target) of a specific translator. To include this or that translator in a given translation process. To read a history of the achieved translations of each translator.
Marking translators as "good" or "bad" can become a necessity, in some sites, however it is way to brutal and blind and should not be allowed so raw. It is much better to assess the capacity of a translator to deliver on time, to spellcheck, to work under pressure, etc... since all those qualities can be independent from one another, i.e. you can find translators who never make spelling mistakes and never deliver on time, so that you can not qualify them as simply "good" or "bad".
The translation manager should also be able to customize categories of expertise. For instance a translator can be an expert, remarkably good at medical, and terribly bad at legal translation.