My thoughts are something along the lines of Ringo. Ringo got a lot of flak for playing too "simply". (ha ha) Blues (not modern blues) with drums are similar. People hear early blues that have drums, and the drums mainly keep time. Of course there are exceptions. Howlin Wolf made his share of exceptions. It's my opinion that the guys who came afterwards wanted to up the game, drumming-wise. (and guitar-wise) But that made it into blues rock, not blues.
With blues, IMO stripped down beats work best. Blues phrasing, which to me means playing a guitar line, then leaving some space before the next emotional statement...that really gets me. Call and response stuff. Build that up to a peak then drop it off the cliff. Dynamics, the building and collapsing of volume, rebuilding etc. for the next soloist, keeping strict time, and authentic-ness...trump fill based drumming. In Blues. It's all about the beat, not the fills. Any fills I use tend to be long tones, press and double stroke rolls, not single stroked tom fills. Unison triplet buildups go well too in the right spots. I'll single stroke for endings, but generally speaking, not during the song
Blues Rock is like Rock to me, anything goes. Blues phrasing is emotional. Heartfelt. Not technical wow factor stuff. It's controlled (to a certain extent) yet highly emotional, that's the beauty of it. Blues have that great balance of restraint and freedom.
It's hard to hold back when playing blues. To substitute it with subtle, even more powerful stuff. It's a real re-thinking of the usual go for broke mentality. Keeping time just plain works.