Their biggest issue by far is fastballs. According to Statcast they are 6th worst against 4 seams and 7th worst against sinkers. I'm not sure how to parse it for velocity but clearly they really struggle against it far worse than the average team. The thing is, they only really thrive against cutters and they're middle of the pack against breaking and offspeed. Add it all up and they're a slightly better than average offense that has been sharply trending downward for several weeks.
Happ, Swanson, the catcher position are absolutely killing us is how I see it. Happ needs to get his HR stroke going and his numbers will blow up. Since the grand slam he's hit 183/329/200/70 with 1 double in 73 PA. Allowing far too many PA end in a walk or K and simply not being aggressive enough on pitches in the zone. Swanson is at 176/243/275/52 since his little 10 game hot start. Amaya and especially Gomes have been aboslutely atrocious. Gomes has a whopping 0:21 BBK in just 55 PA. You can't continue to play that. See what Casali or the other dude can do. They might suck equally but give it a shot.