The new church site was more convenient and better positioned.
Items that were considered important and necessary were moved from San Giovanni Lo Vecchio di Ibla (St. John the Old of Ibla) to the new church.
The old site is described in a document from 1737. It portrays the former site as a horrible space on a precipice and leaning against a mountain.
Not only that, but according to the text, restoring the church of St. John the Old meant reinforcing the foundations, digging into the mountain and spending a lot of money, only to make do with a church not suited to its functions.
So a new, flatter site was chosen, one no longer squashed up against the town walls.