Don't take this the wrong way but the grades are beyond generous. Rowdy with his .305 OBP and below average defense deserves at best a C and no way a B+.
If Wong doesn't get an F I don't know who would but I won't argue too much with a D. I like Adames and appreciate the power and defense but I can't give a grade higher than a C for a player with a .220 average and OBP below .300. Urias deserves a D as he should be a high average, high OBP guy and he has been neither.
The infield as a whole deserves a D as not one of these guys has outperformed and Wong in particular has been completely awful.