Matt Schofield, Robben Ford, Diminished Scales and The Cool Riff
A few things came together for me. I listened to Matt Schofield a lot, and was intrigued by some of the jazzy sounding things he was doing. With my world view of basically "Pentatonic + some extra notes", it was very hard to understand, even if I could transcribe his solos. A guy on jazzguitar.be pointed me in the right direction - the diminished scale when I posted a question about the Djam solo. After that, things started to make a bit more sense, and I went through many, many attempts at figuring out his fingerings before achieving enlightenment.
An important step was reading an interview with Schofield in Premier Guitar, in which he describes having the same experience I had when listening to him, when he heard Misdirected Blues by Robben Ford. If you haven't heard this track, you owe it to yourself to listen - the playing is incredible. Listen to Misdirected Blues at 2:09, then listen to Every Day I Have The Blues from The Trio, Live, starting at 4:19. My point isn't that I caught Matt Schofield copying Robben Ford, but that it's cool to see where he got it. And a cool jazz guy would undoubtedly tell me that Ford got it from someone else.
Here's Matt Schofield playing the riff, and here's Robben Ford. Finally, here's a track that starts with Ford, then plays Schofield, where I have changed the key of Schofield's riff from Bb and C and slowed him down from 135 to 110 BPM to match Ford.
Then, after a lot of transcribing and navel-gazing, I came across this excellent video on youtube where a guy explains the exact same riff (and more)!