OPS is a flawed statistic because it places an equal emphasis on OBP and SLG. They're not. OBP has a scale that maxes out at 1.00, while SLG can go higher than that. That being said, it undervalues some players and overvalues others. You'll find that a player with an OBP of .300 and a SLG of .600 will have the same OPS as a player with an OBP of .400 and a SLG of .500, yet the second player generates more runs.
The way to fix this is 1.8 * OBP + SLG, and if you divide it by 4 you get a number scaled to batting average (this is called Gross Production Average).
Davis: 0.302 GPA
Smoak: 0.295 GPA
That's...much, much closer than what OPS would make it seem. Smoak is also playing at a higher level than Davis is. Davis is also striking out in about 6% more of his plate appearances than Smoak is, which doesn't translate well.