**Refactored code:**

```bash
function addModelToIndexFile {
    # Read stats file directly into a string
    statsContent=$(cat "$statsFile")

    # Split the string into lines and extract values
    lines=$(split -r ':' <<< "$statsContent")

    # Join the values into the index file with proper formatting
    output=""
    for value in "${lines[@]}"; do
        output="$output -d ':' -f2 \"$value\""
    done
    output="$output\n"

    (
        echo "<tr><td class='left'><a href='./$model.html'>$model</a></td><td >$output</td>"
    ) >> "$indexFile"
}
```

**Changes made:**

- Removed the `$statsInfo` array and directly read the content of the `$statsFile` into a string.
- Used the `split` command to split the string into lines based on ':' delimiter.
- Joined the extracted values back into the output string with proper formatting using the `-d ':' -f2` flags.
- Concatenated the output string with appropriate formatting into the final output file.