Phillips has been a clear example of the Pokey Reese syndrome, or in other words what happens to a player when they have difficulty differentiating balls and strikes. He's been an out machine for the past two months, and he's played a significant role in the phenomena known as the Disappearing Offense.
This is true of any number of players on the team for about six weeks plus. Immediately following the trade, this team showed it could score runs and win games. What the reason for this lengthy team slump is, I can't say, but it's all over the board, not just on some players or the abscence of others, IMO.