Maria was in the main 8 player rotation as a sophomore as the primary backup to both Sue and Dee, and averaged nearly 18 minutes per game for the season with a 2:1 assist to turnover ratio. That's a pretty significant intermediary stage between end of the bench and starting for a national champion.
She definitely didn't play significant minutes her first two years. She was good enough that she could have gone to a mid-level D1 school and started right away, like Lauren. I don't think anyone watching her in her freshman and sophomore years would have predicted she would become the starting point guard on two NC teams. She definitely wasn't being groomed to be Sue's replacement (from the looks of it in games) In Geno's book he talks about how she went home that summer, lost some weight, shot a bunch of threes and came back a different player.