And just for another point of comparison:
Kyler Murray: 68.1% completion% (94 for 138), 8 total TDs (7 passing, 1 rushing), 2 interceptions, 194.4 passing yards/game, 99.1 passer rating
Justin Fields: 67.6% completion% (92 for 136), 8 totals TDs (5 passing, 3 rushing), 1 interception, 192.2 passing yards/game, 97.1 passer rating
They also have basically identical Y/C (10.4 for Fields, 10.3 for Murray), Y/A (7.1 for Fields, 7.0 for Murray) and AY/A (7.47 for Fields, 7.41 for Murray). The only difference between the two is Murray is getting sacked a bit less, but otherwise Fields is performing entirely in line with Murray. If you're pulling Fields with this kind of performance, it just shows that you never intended on giving Fields a real chance to be the starter in the first place.