elasticsearch _score not matching explanation.value

_explain

curl -XGET localhost:9200/test/title/1/_explain -d '{
  "query": {
    "multi_match": {
      "query": "matching",
      "fields": [
        "_all"
      ]
    }
  }
}'

_search

curl -XGET localhost:9200/test/title/_search -d '{
  "explain": true,
  "query": {
    "multi_match": {
      "query": "matching",
      "fields": [
        "_all"
      ]
    }
  }
}'

create index and populate data

curl -XPOST localhost:9200/test -d '{
    "mappings": {
        "title": {
            "properties": {
                "name": {
                    "type": "string",
                    "boost": 100
                }
            }
        }
    }
}'

curl -XPOST localhost:9200/test/title/1 -d '{
    "name": "Score not matching title"
}'

The _explain call is returning "matched: false" which is not correct.
And the _search is actually returning result with the _score not matching the _explanation.value which is 0.