How was hiring Brinkley a poor decision by Bertram in the novel, Thank You, Jeeves?

Over the course of the story, Bertram's poor decision to hire Brinkley as Jeeves' replacement becomes increasingly evident. First, Brinkley disappears for a whole night and day, returning to Bertram's cottage drunk and acting outrageously. Eventually Brinkley, he even causes the cottage to burn down. Later, Brinkley takes up residence in the abandoned Dower House and chases Glossop away. The following morning Brinkley gives Mr. Stoker a black eye by throwing a potato at him when Mr. Stoker goes in search of Glossop.