To clarify, this is in relation to calls at Longport just north of Stoke, not to be confused with Longton just south of Stoke, which retains calls on all services. Most Longport calls have been transferred to the WMR service as you say; the WMR service is also diverted via Bescot from May to allow it to serve Willenhall and Darlaston stations, which are currently under construction. This diversion increases journey times from Alsager, Stoke, Stone, Penkridge etc. to Birmingham, but helpfully forms a half hourly clockface service between Crewe and Stoke in the westbound direction, and a 20-40 service in the eastbound direction.
Eliminating the Longport call enables the EMR service to have a slightly longer turnaround at Crewe - increasing from around 8 to 11 minutes in the 'standard hour'. Still very short but it should help a little with reliability, particularly as the WMR service will no longer have to wait for the EMR service to arrive off the single line.
Unfortunately one diagram remains withdrawn and so there is still a gap in the service every 5 hours. This means both the ~8am arrival into Crewe and ~5pm departure from Derby are missing.