Red Sox third basemen in their first two MLB seasons:
WM 169 G, 660 PA, 75 R, 32 HR, 103 RBI, .254/.294/.462/.756, OPS+ 102
RD 179 G, 730 PA, 93 R, 31 HR, 96 RBI, .254/.311/.449/.760. OPS+ 100
Of course, Will Middlebrooks was three years older than Rafael Devers in those respective years.
With some confidence I suspect Devers will have a better career than Middlebrooks but a wide range of outcomes is possible.