I think Hall's getting AB's at RF when the matchup is against a particularly tough lefty. Hermida is not good against LHP, which is why Hall's ability to play the OF is very important.
Hermida lifetime vs LHP: .697 OPS
Hall lifetime vs LHP: .810 OPS.
If Drew goes down for some time, then you have the perfect platoon in Hermida/Hall. And Drew's gonna go down for some time, and half the board's gonna go apeshit about it.