The team is full of players who have underlying statistics that support better than the production they've contributed this season. This applies to all of Bo, Springer and Kirk who have drastically underperformed compared to their expected stats.
I don't know specifically when Kirk turned around his quality of contact as I haven't dug that directly into the numbers, but you can search his expected stats using Statcast search. Using the same dates I've referenced Kirk produced an xwOBA/wOBA split of .161/.235 for the first two weeks, compared to .361/.320 since then.