(1) A different set of expectations for a guy making 8.5M versus 500,000.
(2) It's great that Pomeranz had an excellent 2017 season, but he didn't exactly endear himself to Red Sox fans by laying an egg in the playoffs.
(3) Johnson was drafted and developed by the Red Sox -- fans usually feel a closer attachment (and more tolerance) for players like that.
(4) Brian Johnson has been a better pitcher this year.
(5) True, when we compare their last start, Pomeranz gave up 2 runs, Johnson gave up 4. But Johnson faced a better lineup on a bigger stage (the Yankees) and had better peripherals 2 BB and 11 Ks. In contrast, Pomeranz walked 4, hit 2 batters, and had 3 Ks. If we look at the peripherals, Johnson was quite impressive whereas Pomeranz was the same old s***.