I know I'm not necessarily qualified to be making these suggestions, but these are some of the problems I've noticed after playing 3s. I'm a gold ranked 3s player (StevieHawking), and have been playing this game for two years. Here goes.
-Bruisers are still the kings of this format. Why? Bruisers have often dominated 3s because they come with sustain or free stats. These stats are balanced for 5 opponents, making them incredibly hard to kill. Furthermore, 3s normally don't last long enough for other champs to get to their late game, when most bruisers start to fall off. What Riot did to try to fix this: -New items: A good idea. Make items that let non bruisers have a way to deal with people who have large health pools.
Alters providing extra gold per minion kill accelerates item builds compared to level, which helps. However, as will be discussed later, snowball comp stops most champs from being able to have an effective farming period to take advantage of this. -why it's not working: Bruisers can build those items too, and in many cases, it's strictly better on a bruiser. Like Blade of the Ruined King. Unbelievably good item, especially against an opponent with a large health pool. However, with it having a smaller range than every ad cary's auto range, the active can only be used offensively with melee units. The fix: Tweak items to be different for ranged units or melee units. This has been done before (phage, ghost blade, ect.). With Blade of the Ruined Kings, for example, make it's range have a minimum of the current range OR your aa range, whichever is larger. This makes the item a much more useful kiting tool for ranged champs.
Bruisers also have a HUGE advantage over ranged units because there are no wards. This makes it impossible to gain vision around corners without walking around them, or having an item taking up a slot with very poor stats (grez'z or sweeper). I can understand that wards might become far too powerful a tool for map control, by making it impossible to press for objectives with very little money.
Solution: Wards won't work. With two wards on that map, you can completely zone out the potential for any aggressive play. However, having a consumable that has the same active as grez's lantern with the same area, range and effect as their pink and green ward counter parts would solve this. It would still take up a slot, but the investment would be far lower, and not be on a one minute cooldown.
Snowball comp is easily the strongest comp. Because of the map's set up, the aggressor will have an advantage in early fights.
The main cause is the speed shrine. This allows level one comps to rush into enemy territory, receiving a buff, and secure a first blood against a jungler or any defending teammates. From there, if a jungler decides to invade, because of the lack of wards and shape of lanes, their teammates will reach them at the same time as the defending players. This causes an environment which again gives an advantage to the aggressors. Solution: Take out the speed shrine. It's a nifty addition, but it gives too much of an advantage to early came comps, and prevents people from running champs who scale a little later into the game even more.
Not necessarily a problem, but because it is impossible to ward vilemaw, it is impossible to smite steal it. This makes junglers who can run an offensive summoner over smite have a big advantage because it is not a useful summoner outside of early game. If you want to bring junglers with smite into the meta, let there be a way to purchase vision on vilemaw. Maybe a vender who gives vision of the are for 2 minutes for 100 gold.
The wall adds 5 seconds to respawn times, making it harder to defend Nexus than inhibs. Might not be an issue, but this prevents turn around, almost completely. This makes snowball comp even stronger.
Make the wall at spawn into a barrier impassable to enemy minions, but that champs can go through.
-Make the new items better for ranged units than melee units.
-Make a stackable consumable in place of wards that lasts for a brief period of time and costs a small amount of gold to let ranged champs use their range in fights.
-Take out the speed shrine.
-Let there be a way to get vision on Vilemaw for smite steals.
-Make the wall at spawn an anti-minion barrier, not anti champ.
OH, and make there be a draft pick. The format NEEDS bans, and practicing without them is next to impossible.