Maybe nvalvo's approach is the better one here -- that the organisation as a whole bears responsibility for this. Or maybe JBS9 is right that the buck should stop with the manager. But something needs to change, because it didn't work this past year -- at least if the goal is a significant playoff run.
The problem this year is that all the backups were injured or ineffective, too.
Holt and Hernandez were supposed to be the backup infielders, but Hernandez went down before the season started. Then Holt got concussed before Sandoval was released, so Marrero and Lin had to come up, and neither could hit. It wasn't clear either were an upgrade over Xander after he got hit on the hand.
On the other side of the infield, Hanley couldn't play first all year and Travis was terrible, so they ended up having to stick with Moreland even after the broken toe.
Young never got it going, so it was hard to sit any of the outfielders. Trading for Davis seemed like a good idea, but he couldn't hit after joining the team, either.
The trade for Nunez worked out for a bit... and he blew out his knee.
There was just a ton of shit injury luck. Even a return to average health next year should result in a huge step forward offensively for the team.