Have a look at how many goals we conceded from inside the 18 yard area in Martinez second and third season. By his own admission, he didn't care how many goals we conceded as long as we scored more.There was no change in the system form 1st to 2nd season. What happened was that opponents pressed us much more and the players we had at the back (apart from Stones) couldn't handle it.
He needed cash to upgrade the defence and the GK. His biggest fault in that 2nd season was buying Funes Mori and not VVD.
The thing is, he was too naive and tactically inept to realise that we didn't have the quality to play his way.