You also have 6tph into Vic from Rochdale (3 Leeds, 1 Blackburn, 2 Rochdale). From the west, assuming you have diverted the Atherton line on to Metrolink, you have at least 8tph from Bolton (1 Scotland, 1 Cumbria, 2 Blackpool, 2 Southport, 2 Blackburn/Clitheroe) and 5tph from the Chat Moss (2tph Chester/N Wales, 2tph Liverpool stoppers, 1tph Wigan via Golborne), plus your 4tph of Ordsall Chord metro. Total 17tph, assuming some of the above constitute your Vic - Salford Crescent metro.
Even if you can match routes/paths up to make 12 through services, 17 into 12 won't go, so you need to expand Victoria to terminate at least 5tph from the west.