.717 is not good, I agree, but it's not "terrible" for CF'ers.
Only 22 CF'ers qualified last year.
The AL CF OPS was .702 in 2018. Yes, there were better hitters who played CF last year, but JBJ was not terrible. He hit above the AL OPS for all CF'ers. I agree, that does not make him a "good" hitter or above average, but he was not terrible.
JBJ placed 10th out of 17 AL CF'ers with 300+ PAs in 2018. Not good. Not terrible.