Arrow: 10 Mistakes It Must Fix In Season 5

This ties into some of the problems with stretching the show out over 20+ episodes. It's not possible to have the Big Bad appear in every episode, or at least every episode be related to them, so you need some minor villains to fill in the gap. The villain-of-the-week is a well-worn trope, from Buffy The Vampire Slayer to The Flash, and when done well it can make for some great episodes and memorable villains.

Arrow itself did this well in the early days, whether it was villains in one episode or those who had mini-arcs, from Constantine Drakon to the Clock King, two versions of Count Vertigo, and Huntress. Even Season 3 had Brick, who just about kept things alive when Oliver was MIA.

Arrow Season 4 relied heavily on Damien Darhk and H.I.V.E., and there was no one there to fill in the gaps when they had to take a break. Brie Larvae was borrowed from The Flash late on, and was about as good as it got. Cupid was annoying (again), and Vandal Savage didn't work here, let alone as the main villain on Legends.

Going forwards, they could do with introducing a good variety of villains, and giving some of them multi-episode arcs - it'd reduce the chance of them being instantly forgettable, and put less pressure on the main villain (Neal McDonough is great, but there's only so much he can do).