It's both but maybe the pitching is a little worse. Last year they averaged 4.61 runs and allowed 4.23. This year they are at 4.08/5.53 (and that first number includes the Marlins blowout).
In tonight's game story Turner noted that Long had noted that the team was hitting .280 collectively in the first 12 games. That's very high, and if they keep that up, the RISP will eventually come around. But they need the dingers too.
And they really need the bullpen. I'm not sure we're gonna get impeccable six and seven-inning starts from this rotation which is why they stacked up relievers. I think Nola will be fine and Suarez will be back but if both Soto and Kimbrel fail and Dominguez struggles what looked like a strength just won't be (especially if Strahm stays in the rotation).
Of course you don't need the bullpen to be important if you have both a better offense and better starting pitching