Looking at history, the Oakland Raiders had a top-4 offensive line in both 2016 and 2017. They were ranked No.1 and No. 4 in pass blocking efficiency. So it might come as a surprise that they were one of the worst in the league in 2018.
If you think about it, the only significant difference from 2016 and 2017 to 2018 was they replaced Austin Howard and Marshall Newhouse, who were average, with first-round pick OT Kolton Miller.
Of course, the Raiders also had Donald Penn shift from LT to RT.
But overall, the core guys including Rodney Hudson, Gabe Jackson, Kelechi Osemele, and Donald Penn were all still playing for Oakland.