I am concerned about this particular autograph being signed in person. I am particularly concerned about it being the autograph that he is signing in the proof picture. If I was told that it was signed privately I would say that it appears to be typical but still has concerning characteristics. Post the one that you own and we can compare them. Yours may be fine.
I have about 7 in person Pacino's all from when he did Broadway over the years. One was really nice(2010) similar to this, but even neater if you can believe it. The others were all basically his sloppy rushed autograph. As noted, he has many different (sloppy) styles. This could be legit. I would try & find out more about the rep of the seller and look at his other items for sale and if they look ok or not. It is almost impossible to authenticate Pacino, unfort.