Yeah, I'm not sure if 2M or something else would have been the magic number to go to UMass. I've got no clue, but staying put for 300-500K less is in itself pretty remarkable, and I don't think most Bona fans have stepped back to objectively appreciate how significant that is.
As far as Martin, he may very well end up doing a good job there, but there are 2 ways to view his resume. View 1: He revived K State basketball and reached the final four at SC. View 2: he rode Huggins' momentum into a run at K State, that launched a job offer at SC. There, he reached just 1 NIT and 1 NCAAT in 10 years- his one NCAAT being a final 4, inflating the perception of his success.
I can't think of a hire that symbolically fits UMass and their program better than someone with a resume like Martin's. For the sake of the A10, I hope he does well, but I'm not sold.