you can't compare a recent Steiner Aaron signature with one like this that is over 20 years old. His style has changed drastically. Here is a JSA that would make a better comparison.
I actually have heard of All American Authentications. They were a legit company that actually did do signings with notable sports figures in the mid-1990s in California. I did some research on them several months back when I was trying to work out a deal with the seller of a Wilt Chamberlain autographed basketball that was certified and witnessed by AAA about the same time period as yours near LA. The autograph was a spot-on Wilt sig. I also verified that Wilt was at the event they described. I don't think they're still in business, but they were legit.
I think you can be rest assured your Aaron and Banks balls are authentic.