Bard only has 1 useful ability and leaves his ADC 2v1 most of the laning phase
So, Bard only has one useful ability and that is his ultimate. Overall, as a support champion he leaves his ADC 2v1 because he relies on his roaming ability which leaves your ADC susceptible to being dove or just zoned every CS, making him useless all game. On top of this, his ganks are weaker than champions like: Nami, Annie, Thresh, Blitzcrank, Braum. His heal is weaker than Nami's, Sona's, Soraka's, and Taric's (Although Taric's is less mana efficient), his tunnel can be used by both teammates and enemies, being slower than Thresh's lantern, and allowing enemies to knock people out of the tunnel and damage them while inside the tunnel. The only useful ability he has is his ultimate, which if it's not positioned perfectly this is a useless ability anyway. It can be used to disengage a fight which is only good in certain situations. However, if you use the ultimate to avoid an ability like Ziggs' ultimate or Jinx ultimate, it sets up the enemy team to destroy your back line as soon as you're out of it JUST like Zhonya's.
Note: He is a fun champion to play, but overall an extremely weak one. Damage is subpar, heal is subpar, ganks are worse than other champions and that is what he excels at, and his team fighting is weak. Overall this champion needs to be MASSIVELY buffed or reworked to be viable competitively.