What softball position does this player fit into?

I am an istant coach for a women's fastpitch team at a D3 college. We have two very athletic players one who has a great arm, great glove, and she is fast. The other girl is very fast, has a good glove and a not so good arm. Right now the first girl I mentioned is playing right field and has made some steller outs by picking up a ground ball and firing it to 1st. She is our best and most athletic outfielder and she's only about a half step slower than the other girl. The other girl I mentioned is playing center field and she's playing that position good too although she does have some mental stability issues and I'm not sure she can handle center field. This center fielder played right field last year and our current right fielder sat on the bench all of last year. The first girl that I mentioned has shown a dramatic amount of improvement this year which is why she is starting and I have no doubt in her ability to make every play that comes to her. She is very confident and aggressive and our current center fielder doesn't go as hard, she's more cautious. My question is should we keep the better player in right so she can make those key outs at first base or should we move her to center where she will get a lot more action?