There have been problems with the junction south of Wigan NW where trains access the Hindley lines, with failures on several occasions this year meaning Southport trains terminating at Wigan NW, and Wigan NW trains having to run into Wallgate. Annoying though yet another recast of the timetable is (and, in my view, it's the wrong decision anyway) it does at least remove that point of failure by limiting running into NW from Ince.
What I genuinely don't understand is why Southport passengers want the service they're now going to be getting. The Alderley - Wigan trains are rammed, even off-peak services can be hideously uncomfortable. And the tortuous plod of the Stalybridge services stopping at Kersley, Farnworth, and Moses Gate is soul destroying on the way home from a long day at the office. By contrast, most of the Blackburn and Leeds services are much, much more lightly loaded west of Manchester, even though they're running through to Southport. All this is going to get them is more overcrowding, and less chance of a seat, while people from Wigan use the, now even more lightly loaded, fast services via Atherton.