if most of them are in bronze most of the time, the change won't change that, so you would need to know, for example, how many of them are in gold and for how long, etc.
if e.g. only 5% are 2 days in gold3 with a winrate of 30%. i would consider the intervention too blatant for the effect!
Based on how the ranking system works, as the season progresses and players climb up the ladder, it should be normal that bronze players move into silver. Most real players climb to the top, while bots stay below but still drain the league pool.