dis_max query isn't looking for the best matching clause

I'm testing the dis_max query in the docs below:

PUT /my_index/my_type/1
{
    "title": "Quick brown rabbits",
    "body":  "Brown rabbits are commonly seen."
}
PUT /my_index/my_type/2
{
    "title": "Keeping pets healthy",
    "body":  "My quick brown fox eats rabbits on a regular basis."
}

This example is extracted from the book "Elasticsearch definitive guide" which explains that the answer from the query below would shows equals _score for both documents.

{ 
"query": {
    "dis_max": {
        "queries": [
            { "match": { "title": "Quick pets" }},
            { "match": { "body":  "Quick pets" }}
        ]
    }

}}

But, as you could see, the result from the query shows different _score.

{
  "took" : 10,
  "timed_out" : false,
  "_shards" : {
    "total" : 5,
    "successful" : 5,
    "failed" : 0
  },
  "hits" : {
    "total" : 2,
    "max_score" : 0.02250402,
    "hits" : [ {
      "_index" : "blog",
      "_type" : "post",
      "_id" : "2",
      "_score" : 0.02250402,
      "_source" : {
        "title" : "Keeping pets healthy",
        "body" : "My quick brown fox eats rabbits on a regular basis."
      }
    }, {
      "_index" : "blog",
      "_type" : "post",
      "_id" : "1",
      "_score" : 0.016645055,
      "_source" : {
        "title" : "Quick brown rabbits",
        "body" : "Brown rabbits are commonly seen."
      }
    } ]
  }
}

Elasticsearch is not retuing the _score from best matching clause but is, somehow, blending the results. How may I fix it?