The HAProxy Stats is a great and powerful page. It provides a few abilities:
The HAProxy Stats page gives you a near real-time feed of information that you can use to troubleshoot proxied services, get insights about your traffic, and watch the load placed upon your servers. However, the metrics are labelled using shorthand names and prefixes.
Also the HAProxy Stats page grant ability to manage frontends/backends.
There is option temporarily disable, switch to maintenance mode for backend servers:
Chose need servers and from select menu chose need action, like on picture:
After press the "Apply", page reload and you will see:
Also HAProxy-WI provides the ability to filter frontends and backends by there status. For instance we do not want to see backends what have servers in maintenance status. As we remember we have just setup two servers to maintenance status and we exclude them from output: