Renji has always tried to be as good as Ichigo, but in the end he never will be. Ichigo is just far too powerful and smites down everyone in his path. Renji even got a bankai, but it’s so much weaker than Ichigo’s that he always loses.

If Ichigo fought him at full force Renji would lose instantly. The important part is that this is Renji’s first match so he has to make the most of it. He can’t lose too easily or it’ll look bad for him. The sad part is that he does lose pretty badly in this match. Ichigo wins.