In your opinion, would the club's results have been better without Jones? Your post above would suggest not - if so, then really, the improvement is not down to Bruce as Manager but Jones as a coach.
In all likelihood, given the form prior to Jones' employment, the club would be sitting significantly lower than it is now and probably in a relegation place.
I appreciate the loss of players like Wilson, St Max etc but I think the loss (and impact on form) is more of a damning indictment on Bruce's ability to put into place a decent squad - teams very rarely make it through a season without some losses to key players.
So, is it down to Bruce or Jones - you can't have your cake and eat it ....