iRule sending traffic to wrong pool

Here's your iRule reformatted for easier viewing:

when HTTP_REQUEST {
    switch -glob [HTTP::uri] {
        "/MYExample*" { 
            pool example_pool 
        }
    }
    switch -glob [string tolower [HTTP::path]] {
        "/" { 
            HTTP::respond 301 "Location" "http://[HTTP::host]/abc/" 
        }
        default  { 
            pool abc.com_pool 
        }
    }
}

So a few comments:

1. HTTP::uri and HTTP::path will return pretty much the same information up to any query string data, and since you're only looking for the beginning of any URI, you could combine these two switches and just use HTTP::uri (or HTTP::path).

2. You don't need to do a [string tolower ] if you're only evaluation is "/"

3. You absolutely need OneConnect enabled