This is not going to be a complete analysis, as your intrepid reporter hasn't had much time to do much in the "watch the game for trends" department (9 years results in a lot of excited celebrating and just watching the goals). There were, however, four changes that Arsene Wenger made that were important in Arsenal changing the tide and completing the comeback to win the Cup.
The first change was actually two in one: Yaya Sanogo came on for Lukas Podolski, and Arsenal switched to a 4-4-2, with Santi Cazorla and Mesut Özil the nominal wide players. The substitution and switch to a partnership upfront meant that Olivier Giroud got more involved, and also stretched Hull's defence more: Sanogo ran the channels, giving Arsenal a quicker option, and Özil and Gibbs combined down the left to force Elmohamedy back and create an overlap. Aaron Ramsey got on the ball more, and got into better shooting positions, thanks to a combination of the change, and Hull's midfielders tiring, and being forced to cover more ground.
At 90 minutes, ITV showed Wenger making tactical instructions using water bottles, an indication that he was telling his players to play the ball into the channels for Sanogo to run onto, and then get runners around him and Olivier Giroud, and stretch play.
The final two changes came at the interval in extra time saw Jack Wilshere and Tomas Rosicky replace Özil and Santi Cazorla. Arsenal's two chief creators had tired, but this change made sense as both Wilshere and Rosicky are direct dribblers, with the ability to up the tempo and change pace. Wilshere revelled in the role, playing several incisive passes, including the one that Sanogo laid off to Giroud, who backheeled for the on-rushing Ramsey, who was able to make one of his first telling late into the box runs of the day. The finish was superb, as Ramsey's finishes have been all season, but it was also testament to the changes the manager made. Make no mistake, no man deserves this trophy more than Arsene Wenger.