Here's the deal with SPD: It started on a super high note. The premiere is one of the best PR premieres ever. Idol is one of the best episodes of PR ever. But suddenly, right around Shadow, it petered off. There's a lot of theories as to why, but the show suddenly spiraled away from being a show with a great cast and good stories that just happened to be a kids show, to a kids show that had a great cast trapped inside. Suddenly major plotlines were thrown out right up until the last few episodes, every episode had no connection to any episode around it, and character developments that made no sense just kept cropping up. (The rangers suddenly hate each other in Swat for no good reason.)
After DT, there was hope across the fandom, both from those who loved DT and wanted to see that level of quality continue (me), and those who hated DT and wanted to see something better. SPD achieved it for all of us - and then suddenly fell flat on its face. There's a lot of theories as to why, and most people blame Bruce and hail Greg as some kind of savior, but my personal feelings on it are that Disney started paying attention. Their biggest desire was to have a show that any kid could turn on any day and know what was going on. And SPD achieved that - in the worst way possible.