Hi Sander
For staff the most important attribute is the star rating, 5 is best, 4.5 is good anything less for CD or TD don't bother. For TD and DR you can ignore all of the other attributes.
- For TD all you have to worry about is the star rating.
- For Doctor all you have to worry about is the star rating. However, if finance is an issue this is the member of staff you can get away with low stars and therefore low wages. A low star doctor will slightly reduce your rate of driver training but does not have a direct influence on the speed of your cars. If you want a low star rating doctor, let the contract expire on your existing doctor and the game will auto-assign a replacement at £50k per race.
- The CD determines the starting design for the next season and also influences research. Your primary concern should be to employ a CD with high star rating and secondary should be the strength and weakness. Ideally strength should be one of Acceleration, Brake, Downforce or Handling combined with a weakness of Reliability or Cooling. Unfortunately these CDs are as rare as rocking horse sh*t so you'll probably need to compromise on the strength and weakness. If you research the strength of your CD you will get more points than your research power indicates and if you research your CD weakness you will receive fewer points.
Be aware that the star rating is inversely proportional to the difference between your manager level and staff level. Staff never level up so this means as your manager level increases so the star rating will drop.
I hope this helps
Kev.