"There is definitely going to be a different look. The Padres made a major transition midway through the 2009 season. It has transitioned again. I like this team. The focal point of last season was always Adrian (Gonzalez). We’re more balanced. That balance has to make up for the loss of Adrian."
That will be tough to do since in the last two years Gonzalez finished 4th and then 2nd in WAR with 7.0 and 6.3 (from Baseball Reference). Black said they will be improved elsewhere. That might make up for losing Gonzalez, but it does not have anything to do with balance per se.
I have done some research on balance. See
The Impact of Lineup Balance on Scoring, 1920-89
Are "Balanced" Teams More Successful?
I found balance helps very little, if at all. I also have links to research by Keith Woolner and David Gassko at that first site. It looks like their research shows that at most better balance can add 1 per season. So if Adrian Gonzalez's replacement costs the Padres more than 1 win compared to him, the balance will not help, as Black says. That is assuming that they actually are more balanced.