I wouldn't recommend it. Google will give you good results for traffic, but not good results for ROI.
I've had private Google account managers help me manage my accounts and I had to go back and change everything they did because all they really only know is how to increase your CTR and average Position. What they do not know is how to do is to eliminate irrelevant searches, stop your ads from displaying during pre-sell your visitors in your text ad, and increase your revenue.