The default Kicker rating is:
Kick Strength 100
Kick Accuracy 100
General Attributes (Strength, Speed, Acceleration, Intelligence, Discipline) 20 each
Default Kickoff rating:
Kick Strength 100
Kick Accuracy 40
General Attributes 20 each
Default Field Goal rating:
Kick Strength 40
Kick Accuracy 100
General Attributes 20 each
General attributes weigh more heavily in the specialization ratings (5/12 instead of 1/3). Your Kicker's position is
Kicker, so he also gets an out of position penalty to his rating at either specialty (about a -4 from his current rating). Those weights can be adjusted just like any others.