How comes the service to Middlesbrough has now been extended to Redcar Central?
I think it might be to improve reliability by reducing congestion and delays at Middlesbrough (a more heavily used station) upwards instead towards Redcar Central (a lowly used station) for extra room available for turnarounds to restart service back towards Manchester.
I doubt Redcar Central is likely to be used as a 'real' destination and may find itself being cancelled more often than not when delays occur. Currently, the Middlesbrough service tends to be regularly delayed, and the Dewsbury stop gets 'cancelled' due to 'operational difficulties' or some other excuse so that the train can catch up time and reduce total delays. However, this causes lots of customer dissatisfaction so bad statistics for TPE, so now they can use the time to call at these less important stations on their route and instead cancel Redcar, which would not cause much inconvenience to Redcar passengers as it is an extra 1tph service and is instead normally regularly served by Northern anyway.