Don't agree with you entirely as Martinez in his first season was excellent. You cannot possibly fluke a whole season purely because you inherit a squad, and there were many occasions in that first season where Martinez' ideas were positive and he even proved a lot of doubters wrong with changing games with positive substitutions that weren't necessarily popular with the fans. I clearly remember our fans groaning at his decision to bring on Osman in the away game at Aston Villa for example (myself included). Osman came on for Barkley in the 60th minute, and changed the game, getting an assist and a goal to win us the game:
http://www.bbc.co.uk/sport/football/24591399
Fast forward to a year later and the same Martinez who had been a breath of fresh air the season before stood on the sideline without making a single subsitution as we slumped to a 0-3 defeat at the hands of Southampton who were on a 5 game losing streak:
http://www.bbc.co.uk/sport/football/30459790
He became far too subborn and got carried away with the hype and believed he could now do no wrong. The 2 seasons after his first were shambolic and he set us back considerably and that is where I agree with your disgust for him.
We're now back to where we were pretty much and there can be no excuses from the board this year. We have the money, we will be playing in Europe next season and we have hugely ambitious plans for the future. Koeman, Moshiri and Walsh need to get it right this time and they can't hide behind excuses like they did last summer. It could be a very exciting summer though if it turns out how we hope.