I'm not sure that I trust one good year, Valencia had one good year, Diamond has one good year, Plouffe had an okay year.
Valencia got lucky and many were predicting a step backward. Maybe not a giant leap and then fall-on-his-face backward step, but regression none-the-less.
Plouffe was only good for ~45 days. The rest of his season was bad. Not even mediocre, just bad.
On the other hand, Dozier actually looks like the player we were told about in the minors. Steady hands, solid glove, good strike zone judgment. The only surprising thing is the power, which might decline next season. To boot, Brian's BABIP is quite a bit lower than expected, particularly for his style of play. He's not a speedster but he's not slow, either. Any downtick in power has a good chance of being balanced by an uptick in average and OBP.