Due to various reasons, champions that were once the most beloved in League of Legends are now hardly played at all. Here is a list of those champions that are very underwhelming:
Rengar

Rengar was once one of the most popular assassins in League of Legends with his combo dealing thousands of damage in less than a second. Even his “leap” mechanic while standing in bushes was very much loved. However, now the Pridestalker has been shunned by the community, with his jungle pick rate in ranked mode even lower than that of the rarely played “tank” champion Amumu.
Many believe that Rengar’s risky “high stakes” playstyle is gradually fading from League of Legends due to the plethora of “insurance” options in the game such as Zhonya’s Hourglass, Guardian Angel, and many champions that provide excessive healing and shielding buffs.
Riven

Riven was once one of the most beloved champions in League of Legends due to her extremely captivating playstyle. With impressive skills used for both “dancing” and 1v1 duels, Riven was adored by the community for a long time. The numerous beautiful skins released by Riot Games, such as Battle Bunny, Championship, and God-Slayer, also signify the popularity of this champion.
However, in the current meta, even in normal matches, very few players choose Riven, let alone ranked games. It can be said that this champion is “hiding in the bushes” partly because of the overwhelming strength of new champions, and partly because Riven’s kit is gradually becoming “outdated”.
Shen

In the past, Shen was the top-loved top laner in League of Legends. With an incredibly perfect kit that included healing, poke, crowd control, and effective teammate protection, Shen became even more dangerous when chosen by experienced top lane players.
After a rework, it cannot be said that Shen has become weaker, but his popularity has significantly decreased compared to before. Especially when compared to a host of champions in the current meta like Irelia, Sett, and Volibear, Shen is clearly outclassed in terms of popularity.
Ziggs

As one of the few mages capable of destroying structures faster than both marksmen and fighters, Ziggs once “peaked” in the meta when he was used in the bot lane. But now, the Demolitions Expert is buried by the strength of new champions. Besides having a skill kit that relies heavily on skill shots with little reliability, Ziggs also lacks mobility to roam aside from his easily dodged ultimate.
Ryze

Ryze is a champion that Riot has paid special attention to with numerous reworks and power adjustments throughout the history of League of Legends. Once used by Faker to dominate in professional tournaments, even maintaining a winning streak with Ryze for many years in the international arena. In those years, Ryze was played everywhere from top lane, mid lane to bot lane due to his overwhelming damage output.
However, in the current meta, very few players trust Ryze whether in ranked matches or professional play. The rise of other powerful champions has pushed champions like Ryze to the bottom of the meta.