I'd say the episodes of the anime were simply stand alone not lacking in cohesion.
It's flawed, very flawed, but for a video game anime from the 2000s, I think it could have turned out much, much worse.
No, I know what I said and I meant it. It
lacked cohesion. If it were
just stand alone monster-of-the-week episodes they would've ideally put in more work into the individual episodes instead of wasting the characters in them with barely any action from a studio known for its action scenes. If they wanted an overarching plot from the start then it shouldn't have been the generic take-over-the-world plot from Sid acting like a bootleg Arkham. He should've gotten killed on sight and instead Dante's Plot Induced Stupidity let this guy collect pieces of unrelated demons to open a gate in episode 11 to "a demon that could rival Mundus", and no part of that makes sense: Abigail has Mundus-level power but could be sealed by a random sorcerer we've never heard of; the barrier is so potent it works better than any hellgate we've seen in the games; did the demons not know they had pieces of the barrier seal in them?; what makes
them the pieces Sid needs for the seal and not some other demons?; Dante gets overpowered and impaled by Abigail and it's presented as such a big deal that Patty needs to go down and personally un-impale him because he's knocked out, then one episode later he can survive impalements from Abigail and one-second DTs him? Pick a topic, it won't make sense.
As it is, the episodes on their own sucked, and the overarching narrative that kicked in in the penultimate episode with only brief bits of foreshadowing two or three other times
also sucked. There's a reason I tell people only a third of the series is worth watching.