Last year was supposed to be Aaron Altherr's year.
After playing 39 games in a cup of coffee with the Philadelphia Phillies in 2015, Altherr raised eyebrows by slashing .241/.338/.489 with 5 homers, 11 doubles, 6 steals and a weighted runs created (wRC+) of 125. His 1.8 fWAR was second among all Phils position players that year, which is impressive, even if that probably says about as much for the state of the Phillies at that time as it does Altherr).
After that terrific cameo as a 24-year-old, Altherr was essentially handed the starting right field job heading into 2016 spring training.