Glad to see most posters talking about defense instead of offense, but Julien's calling card is and will be his bat. And he needs to adjust at the plate or he will fall out favor, much like Miranda;
April 12 - July 29 splits (57 games): .300/.388/.539 (.927 OPS) 10 HR, 18 RBI, 25/65 BB/K ratio.
July 30 - Oct 1 splits (52 games): .222/.374/.367 (.741 OPS) 6 HR, 19 RBI, 39/63 BB/K ratio.
Play-offs Games 1 -5: .214/.389/.286 (.675 OPS) 0 HR, 1 RBI, 4/7 BB/K ratio.
Play-offs Game 6: 2-3, 2B, HR, RBI, 1/1 BB/K ratio.
He was also often removed from games late for defense and didn't face LHP, including Play-offs.
.741 OPS from July 29 until the end of the season was league average (Gallo's full season OPS was .741, which equated to an OPS+ of 101, league average.). Including his first 5 Play-off games, he was slightly below league average over this period, but finished his season with a very good game against Houston.
Just looking at the numbers, it would appear he tried to work deeper counts, which resulted in more walks and maintaining a high OBP, but came at the expense of a lower BA, a lower SLG%, and an uptick in SO's. He's young enough and skilled enough to hopefully turn it around (and he's off to good start this spring), but he could also turn into nothing more than a placeholder until Lee or someone else pushes him out.