Art Of War mod is partial-conversion modification adding lots of new features to old Zero Hour's gameplay, they are discussed in summary.
General Granger decided that MIM-104 Patriot is to slow and immobile for his rapid deployment forces. Therefore he decided to replace it with much more mobile Humvee-based SLAMRAAM SAM Launcher.
This launcher features higher mobility but lower armor protection. In addition, it doesn't need to deploy before launching missiles like Patriot. Such characteristics as firepower and attack range didn't changed.