Secondly, to take the different aspect of how you can possibly know they migrated. You don't state where you find these other matches, so I'll guess that they are in FamilySearch (FS). The problem is that FS's coverage in England is far from complete, so there could be lots more people of that name who don't appear in FS - never mind those who weren't baptised in the CofE.
There are 2 sites that give explicit information about what's in FS. The original is Hugh Wallis' site and there is a later update from Archer Software. Both sites cover only the original IGI data and do not cover the later stuff that has been added to FS - e.g. Cheshire has now been indexed virtually 100% for Cheshire Record Office. Neither site is helpful for telling you what could have been indexed. For that, you need to try something like the GENUKI pages for the counties in question, list off all the parishes and chapels, and see what their coverage is. Occasionally you'll find a Record Office has done something like that for you, or they list all their own holdings, which tend to be complete for their assigned area, and can serve as an easier basis for checking simply because of their format.
The truth is that picking up someone who moves any distance can only be done if you have explicit indication of their origin. Classically this will be in the census for those alive 1851 onwards. Before that, it's very rare indeed to pick up such a move. I know my 6G Grandfather Purdy moved from Blaydon, County Durham, to Bristol via London in the 1730s but that's only because his son got in touch with his relatives in the North-East, kept the letters (he's described as an accountant) describing the move, and was sufficiently interesting in his own right for the letters to be copied for Bristol Record Office.