I think we will be aiming higher in terms of expected production in left. Keep in mind that Dickerson had a career year (actually a career first half) last year. You don't project future production off a great half-season. His baseline is not that impressive.
No doubt - the earlier point was about lineup balance though. Given that, Dickerson wouldn't make the lineup too left-handed in 2019 if he were still in LF and Riley or Donaldson were manning the hot corner. Acuna replacing Markakis takes care of that.