Thought Cook should have had Mo on earlier, as the commentators keep reminding us he's a 'part-timer' but if he can continue going at 2.5 an over and pick up the odd wicket he can rotate the quicks around him and keep them fresh.
Personally I think Mo bowls enough in county cricket to be regarded as better than part time (but that would involve commentators watching some cricket they aren't paid for) and is the best option until a spinner puts their hand up and demands to be picked.
