From '12-'15, Dyson had BABIP vL of .265, .250, .333, .286...Last season he was Ruthian at .423. Which means that an extra 3 bloops fell, or 3 seeing eye grounders scooted through, in his 26 AB's. He was 11-26, rather than the 8-26 you might expect.
Bet the Under next year.
But vR, he's been pretty consistent. (OBP/OPS) '12=.340/.689 '13=.339/.741 '14=.326/.663 '15=.313/.715 '16=.330/.700
I think the .330/.700 he had last season is the Over/Under line. A fair one, too. His career #'s are .329 and .697.
Danny Valencia is .246-.288-.394=.682 for comparison. But he's terrible vR.*
Actually, if you set Dyson's line at .330 and .700, it is a fair question whether his Over/Under is any better than Gamel's.
All in all: Give me 4 years of Karns.
* '15-'16 indicate he's found his vR medicine, however.