Oh yes they have!
On 2nd April I booked an IOM-BHX return outbound from Ronaldsway at 14.45 on 25th April, returning at 16.10 from Birmingham on 29th April.
Within 2 days I had an email to advise me of changes and am now departing IOM at 17.15 on 25/4 returning at 15.50 on 29/4 both flights now operating on an E175 which will be a BHX based aircraft. Also a look at the timetable now seems to show different times on different days of the week.