Agreed to a point.
But...
Vazquez: .259 for his career - .227 thus far
Jeffers: .220 for his career - .260 thus far
Gallo: .199 for his career - .189 thus far
Kirilloff: .255 for his career - .265 thus far
Solano: .277 for his career - .271 thus far
Farmer: .264 for his career - .253 thus far
Correa: .274 for his career - .212 thus far
Castro: .247 for his career - .256 thus far
MAT: .239 for his career - .212 thus far
Kepler: .230 for his career - .198 thus far
Buxton: .240 for his career - .203 thus far
Julien and Lewis excluded; the former's a rookie and the latter doesn't have enough to data to draw upon. Of the 11 batters, 8 of them are below their career averages - and of the 8, the average drop from the career average is 27 points. Of this group, Vazquez and Solano are the only ones I would term 'old'. The others, at their respective ages, shouldn't be falling off a cliff.
When a group underachieves as badly as this line-up has, someone gets fired - usually the hitting coach or manager. It's hard right now to pin this all on Falvey and Levine when nearly every hitter is failing to live up to reasonable expectations, i.e., their career averages. They didn't all turn into pumpkins over night.