The reason Moyes got more time is that he inherited a much weaker side with less money to spend
And, despite us bumming around lower mid table in his early days, you could see that he was putting together a solid outfit that were just lacking that odd bit of class in certain areas of the pitch
We went from being whipping boys to being a team that were difficult to beat, which eventually culminated in the great finish of 04/05. That's another point to consider as well, Moyes had an awful time in his second full season, like Martinez, but pulled it back spectactularly in his third one, which Martinez hasn't
Martinez can't defend. His defensive tactics are absolute arse. Even if he had a better calibre of player, I think we'd still leak goals
If you gave David Moyes a World Class defense (Which he didn't have at Man United btw) then he might play some dull football, but he'd at least keep it tight at the back
You could give Martinez a back 5 of Lev Yashin, Ray Wilson, Bobby Moore, Franz Beckenbauer and Cafu, all in their primes, and his side would still leak goals at a horrifying rate because he's an awful defensive coach
In the English League, you need to be defensively solid. That's why Leicester won the title this year and Chelsea won it the year before
Martinez would probably do much better on the continent (And he probably will based on his Europa League tactics), but he's shown at both clubs that he's managed in the top flight in England that he's AWFUL at organising a defence. He had one good season in 13/14 with defending, but that was an aberation
THIS is why Martinez doesn't get the same leniancy as Moyes did (And even then I think a lot of people would argue that Moyes should have really left after the Final in 2009)
Moyes at least showed that he could have top half consistency in the English top flight.
Martinez hasn't
He's had one top half finish with us, in his first season before all the other sides sussed out his tactical flaws, and a Cup win with Wigan where we handed them a Quarter Final win, they got the soft draw in Millwall for the Semi Final and they played a City team in disarray who had just sacked their manager on the day of the Final
All the positives of Martinez (The attacking play, giving youth a chance, the positive mentality, the fact he clearly "gets" Everton) are all outweighed by the Chernobyl sized negative of his positively horrendous defensive organisation
Moyes had negatives, quite a number in fact, but at least he could organise a defence and, whether you like it or not, defensive stablility is ultimately more important in this league than attacking flair. You need both to stand a good chance of winning something, but you can survive on being a strong defensive outfit with a "meh" attack. As teams like Wigan, Blackpool and Charlton have shown over the years, it's a lot harder to survive when it's the other way around
Regardless of how much money he has to spend, Roberto Martinez's lack of defensive nous will mean he will never achieve anything in the English League. He may win cups both in England and abroad, but he'll never win the Premier League or be at the helm of a team that regularly finishes in the European places because he just can't keep it tight enough at the back and he's far too stubborn to bring in a top defensive coach to help him