To be honest he is a average to good manager, which is why he was appointed in the first place. I think it is important to bear in mind that in his mind he is first team coach, rather than a British-style manager. Walsh was also in over his head as DOF, and is used to being a UK style chief scout. So basically they were working in a structure neither was suitable for, or at least there was a confusion that transferred over to the team.
He is a decent coach who will do alright at the top level without ever pulling up trees. His first season was pretty good, second season pretty bad, so he is somewhat on a par with Bobby M, though a notch below. We would never have got relegated with him in charge, and I think we just blew a fortune for next to no benefit, other than quelling the mob in the short term.