It didn't help that Brandon Wimbush couldn't see the wide-open WR3 and WR4, not to mention the TE as well, and the fact that he threw a lot of passes that got his WR's clobbered on a regular basis, made it worse. Then when the yips came about, he couldn't complete a wide-open 5 yard pass to keep a drive going.
I don't blame St. Brown for leaving early. He almost had his neck snapped on one pass that was thrown way too high, and ended up with several helmets crashing into his torso on many other pass attempts.