Don't forget, most spring training game at bats are not against top ML pitchers who are in their regular season form. My guess would be that the WBC at bats were as good or better than normal spring training game at bats during the same time period.
If anything, I think they may have had an emotional let down coming back from the WBC. It looked like they really got into those games. Nobody really knows if the WBC helped or hurt the preparation for the regular season, but it is a long season so every player will have ups and downs. Right now, it seems that Turner is struggling to get hits and his BA has fallen quite a bit recently, falling into the .270s until he got the hit in his last AB to go to .280. I am looking forward to some big games from Turner coming up, hopefully soon.