I made posts on this back in the day when Riot used to do the same thing they are doing now until they eventually improved and changed. Currently, Riot balance changes is down-spiraling into a trend of perpetual nerfs and reworks.
Reworking champions is important when they become non-viable due to having a dysfunctional kit rather than just being in need of buffs.
Nerfing champions is important when a particular pick becomes too strong and overwhelming.
Buffing champions is also important for when something becomes underwhelming.
**Here's a supposed example of why primarily relying on just nerfing can negatively impact game balance:**
_NOTE: For the sake of valuable discussion, let us just presume these counter-matchup interactions are correct. Whether or not they are is a separate debate non-related to the primary point of this post._
Example: Let's say the best mid-lane champion based upon competitive pick/ban-rate as well as ranked pick/ban-rate and win-rate is Leblanc. Obviously we are imagining a make believe meta separate from the one we currently exist in.
Let's suppose the 3 best champions to play against Leblanc are: Kassadin, Ryze, and Lissandra.
Let's suppose 3 champions that get countered significantly by Leblanc are: Zoe, Zilean, and Velkoz.
Method 1: (Big Nerfs)
Now, we're going to try to correct the fact that Leblanc is the clear go-to, best mid laner in the current meta by nerfing her. This will either be a set of big nerfs on one patch, or a set of small nerfs accumulated over multiple patches.
Result of Method 1:
Zoe, Zilean, and Velkoz will presumably be picked more in games now that one of their central counters has been hit with some significant nerfs. Kassadin, Ryze, and Lissandra, like-wise, may see less play depending on other factors and interactions with other champions.
Let me put these in even simpler terms:
Leblanc is good against champion A, B, C.......
Leblanc is bad against champion X, Y, Z..........
1. If champions A, B, C are considerably good in the current meta, Leblanc will likely see more play. This will be especially true if champions X, Y, Z are not very strong in the current meta.
2. If champions X, Y, Z are considerably good in the current meta, Leblanc will likely see less play. This will especially be true if champions A, B, C are not very strong in the current meta.
**Subsets of champions, rather than a wide-range, become meta as a result of nerf-focused balance changes. Constant nerfs creates a down-spiral where either case-1 or case-2 occurs depending on how different champions interacted with the champion that is targeted by nerfs. **
Method 2: (Light Nerfs, Light Buffs)
Lightly nerfing the champion that is considered to be overwhelming while lightly buffing the opposition. In our example, this means lightly nerfing Leblanc while lightly buffing Kassadin, Ryze, and Lissandra. This helps to create a meta where all 7 champions in question may be considered to be viable without having one champion that is clearly overwhelming above the rest.
**How do we define a "light nerf" or a "light buff?"**
_Light Nerf:_ Reduction in damage. Reduced such that Leblanc does not overwhelm Zoe, Zilean, Velkoz to the point that you cannot afford to risk blind-picking these 3 champions as long as Leblanc is available. Not reduced so much that Leblanc is no longer considered a viable counter to these 3 champions.
_Light Buff_: Increase in damage. Increased such that the champion in question can successfully oppose other champions without becoming so strong that they have no counters or so little that their counters can be eliminated by just 1 or 2 bans.
**Summation:** From what I have observed so far this season, Riot has followed a trend of nerfing and reworking champions. Rather than increasing the number of ranked or competitively viable champions, this method has the effect of keeping the number approximately the same while simply changing the specific champions that are viable at a particular point and time. Riot should look at the champions that have fallen out of flavor due to over-nerfing and consider a mixed style of nerfs and buffs to achieve balance, rather than relying solely on drastic changes. Buffs to over-nerfed champions should be done to undo some of the previous damage done, rather than trying to go into a different direction with a pseudo-rework. Buffs in general should, while not needing to be overly significant, should have an effect that is seen by how those champions and their opposition interact.