Steven Spielberg Produced the PT
Irvin Kershner (RIP 2010) Directed them
and GL only wrote them and co-produced.
Oh and casting was done by April Webster (LOST, Star Trek) and Alyssa Weisberg (Star Trek, Super 8)
I for one think they would go down as the greatest movies ever made.
In all likelyhood you are correct. There was already a lot of talent involved with the making of the prequels. Lucas simply needed a wingman willing to challenge him, not simply give in to his every whim.
Lucas was sent back to the drawing board several times on the original trilogy, & had people willing to challenge him during the making of those films.
THe difference in the end result is obvious to everyone.