First thought is the the long-track tornadoes indeed followed outflow boundaries from morning rain. However it had to be south of the stable air. While deep layer parameters were lower down there, low-level parameters were maximized (SRH and low-level CAPE). Winds were backed on the boundary and the surface heated up at/south of it.
Second both ARW versions sniffed out the northeast Alabama mess again. HRRR was just crazy. NAM pushed for a big warm sector, but was not as robust as the HRRR. Felt like ARWs caught the evolution best though.
Finally I believe moderate to high parameters, but not pegged out, are best for chasers. How we got there could be debated. Anyway the long-trackers were south of the maxed out indices. Just the low-level details were quite important.