Warner went to a so-so New York Giants team after being railroaded by Martz. The Giants story is largely untold. What we read is that he was replaced midseason by Eli because, supposedly, Warner was all washed up, and stunk.
I videotaped a Giants game against the Packers and Brett Favre until the game was switched off by the network. I wish I could post it because it shows clearly that
Kurt still had it! I forget Kurt's final stats for the game - but the game when the nework switched it off was lopsided. Kurt was slicing and dicing the Packers pass D - at the time one of the best in the league. He delivered, and elevated the Giants to playing playoff-level football before OL and WR injuries knocked the wheels off, two games before Eli took over to all but lose out the season.
Kurt was in a totally different system than he had in St. Louis. He took over the same so-so team that the Giants had fielded for years. He quickly mastered Coughlin's conservative system and brought out the best in his teammates - wideouts told how they had to adjust to the fact that while they were making their cuts the ball was already on the way, and would be there when they turned. His reads were, as they had been in St. Louis, uncanny.
The same attributes that let him elevate the Rams offense to a level above what Trent Green gave it also elevated the Giants to greater heights than Kerry Collins or Jason Garrett could deliver. And the team had to be rebuilt on the fly to rescue Eli Manning. They got a WR with the catch radius of a radar dish in Plaxico Burris. That helped Eli's - accuracy, I guess we have to call it.The Oline recovered. There were new additions.
The reconstituted Giants won to the Super Bowl in 2012. By then Kurt had taken another so-so team, the hapless Arizona Cardinals (earlier the St.Louis Cardinals) to the Super Bowl, and had them ahead when he left the game in the final minutes.
Three teams, four different systems (Martz, Green, Wizenhunt, Coughlin) and Kurt had all of them playing championship-level ball. Given that it takes system, coach, and players to make a winning team, I think the notion that the Martz system made Warner is less true than that Warner made the Martz system.
The success of all those teams, when Warner was their QB, is largely attributable to him.