The magazine has attempted to separate the two superstars' by working out which player has scored more 'valuable' goals
In a nutshell, their argument is thus: "... not all goals are created equal: their value depends entirely on the context in which they occur. Some land in the 90th minute of a 1-1 tie and secure a win all by themselves; others are tacked on at the same point in a match once a team is already up 3-1."
The full article argues that scoring the winning goal in a tightly contested match is of more value than a bonus goal with your side already heavily up - and that over the last two years (their sample size) Messi's goals have been 'worth' a lot more than Ronaldo's, even though the Portuguese has scored 105 to the Argentinian's 86 (goals from La Liga, Champions League and the World Cup).
Using their 'EPA' metric, Expected Points Added, which boils down the minute a goal is scored, the importance of the match and the context of the match (whether the goal was important) into a percentage and then a single number, each of Messi's goals are worth more - 59.5 EPA, compared to 50.4 for Ronaldo.
The article stipulates that goal scoring, of course, is not the only aspect of a match that decides its outcome, defensive play and the ability to create for team-mates has not been taken into account.
But from a purely goalscoring perspective, it would appear that Messi has the upper hand, even if on paper it appears as if Ronaldo has scored more in recent years.