the main difference is that you're comparing team versus team, where as brett and myself are arguing situationally
Yes, when an NL team comes to an AL park, their DH is not likely to be that good of a hitter (or whomever they take out of the field to be the DH, is not likely a good hitter). Otherwise that guy would have been starting. But our point is that it needs to be compared to their normal lineups. Like which lineup is a more potent, offensive lineup?
Dodgers Game 1 Lineup: (@LA)
Taylor CF, Turner 3B, Bellinger 1B, Puig RF, Hernandez LF, Seager SS, Forsythe 2B, Barnes C, Kershaw P
Dodgers Game 3 Lineup (@HOU):
Taylor CF, Seager SS, Turner 3B, Bellinger 1B, Puig RF, Forsythe 2B, Barnes C, Pederson DH, Hernandez LF
Outside of the order, the difference in the lineups is Joc Pederson and Kershaw as the hitter. Kershaw is still pitching normal innings, defensively nothing has changed; the only difference is the offense. And without question, the Dodgers have a weaker batting lineup in Game 1 than in Game 3.
Yes, Joc Pederson may be a worse than Evan Gattis (although in this case he isn't, but generally speaking the NL DH will be worse), but the NL's lineup still gets better while they play at an AL park. Where as the AL team's lineup gets definitively worse when they go to an NL park, because at least NL pitchers have been swinging the bat all season long.