You'll need to regenerate your config or copy the new sections from here.
This new stat is displayed at the very top of of the horse stats message, it's a single number that gives an overall score for a horse (50 being average and 100 being perfect stats).
You can also disable this stat from being shown at all in config just incase you want people to work it out themselves. Currently this score only applies to normal horses because other variants have different averages which would complicate the formula.
You will need to regenerate your config or copy the new one from github!!!
This update adds the ability to use horse stats on zombie horses and skeleton horses as well as adding config options for all messages! (I will probably eventually rework the messages config to make it a bit less confusing this works for now)