yes, well the surname whooley,is pronunced welly,and wooley,by two different families,who only live fifteen miles apart.
likewise niall,can be pronounced neal,but is often pronounced [nile]Ithink the latter is an anglicisation,[not being a native Irish speaker, I stand corrected if I am wrong]
logically it[ni] should be spoken,like niamdh[neeve],but how much of the population does it take , when usage,makes it [nile], correct.